| USD ($) $ in Millions | Jun 30, 2026 | Mar 31, 2026 | Sep 30, 2025 | Jun 30, 2025 | Mar 31, 2025 | Sep 30, 2024 | Jun 30, 2024 | Mar 31, 2024 | Sep 30, 2023 | Jun 30, 2023 | Mar 31, 2023 | Sep 30, 2022 | Jun 30, 2022 | Mar 31, 2022 | Sep 30, 2021 | Jun 30, 2021 | Mar 31, 2021 | Sep 30, 2020 | Jun 30, 2020 | Mar 31, 2020 | Sep 30, 2019 | Jun 30, 2019 | Mar 31, 2019 | Sep 30, 2018 | Jun 30, 2018 | Mar 31, 2018 | Sep 30, 2017 | Jun 30, 2017 | Mar 31, 2017 | Sep 30, 2016 | Jun 30, 2016 | Mar 31, 2016 | Sep 30, 2015 | Jun 30, 2015 | Mar 31, 2015 | Sep 30, 2014 | Jun 30, 2014 | Mar 31, 2014 | Sep 30, 2013 | Jun 30, 2013 | Mar 31, 2013 | Sep 30, 2012 | Jun 30, 2012 | Mar 31, 2012 | Sep 30, 2011 | Jun 30, 2011 | Mar 31, 2011 | Sep 30, 2010 | Jun 30, 2010 | Mar 31, 2010 | Sep 30, 2009 | Jun 30, 2009 |
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Current assets: | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Cash and cash equivalents | $ 1,614 | $ 735 | $ 808 | $ 1,060 | $ 1,411 | $ 947 | $ 1,137 | $ 925 | $ 750 | $ 830 | $ 1,079 | $ 1,267 | ||||||||||||||||||||||||||||||||||||||||
Short-term investments (Note 13) | 500 | 300 | - | - | - | 20 | 20 | 20 | 16 | 0 | 0 | 46 | ||||||||||||||||||||||||||||||||||||||||
Accounts receivable, net (Note 10) | 2,130 | 1,986 | 1,921 | 1,915 | 1,965 | 2,036 | 2,118 | 2,162 | 1,934 | 1,826 | 1,955 | 2,052 | ||||||||||||||||||||||||||||||||||||||||
Materials and supplies | 919 | 838 | 782 | 774 | 747 | 775 | 807 | 770 | 770 | 742 | 728 | 794 | ||||||||||||||||||||||||||||||||||||||||
Current deferred income taxes | - | - | - | - | - | - | - | - | - | - | - | - | ||||||||||||||||||||||||||||||||||||||||
Other current assets | 370 | 356 | 393 | 434 | 416 | 371 | 416 | 317 | 343 | 354 | 296 | 246 | ||||||||||||||||||||||||||||||||||||||||
Total current assets | 5,533 | 4,215 | 3,904 | 4,183 | 4,539 | 4,149 | 4,498 | 4,194 | 3,813 | 3,752 | 4,058 | 4,405 | ||||||||||||||||||||||||||||||||||||||||
Investments | 2,977 | 2,954 | 2,841 | 2,785 | 2,704 | 2,649 | 2,705 | 2,651 | 2,580 | 2,524 | 2,439 | 2,314 | ||||||||||||||||||||||||||||||||||||||||
Properties, net (Note 11) | 60,199 | 59,955 | 59,392 | 59,017 | 58,710 | 58,036 | 57,835 | 57,590 | 57,010 | 56,641 | 56,274 | 55,689 | ||||||||||||||||||||||||||||||||||||||||
Operating lease assets | 875 | 907 | 1,090 | 1,193 | 1,142 | 1,345 | 1,386 | 1,453 | 1,670 | 1,651 | 1,700 | 1,703 | ||||||||||||||||||||||||||||||||||||||||
Other assets | 1,627 | 1,613 | 1,420 | 1,398 | 1,397 | 1,391 | 1,393 | 1,378 | 1,467 | 1,465 | 1,497 | 1,232 | ||||||||||||||||||||||||||||||||||||||||
Total assets | 71,211 | 69,644 | 68,647 | 68,576 | 68,492 | 67,570 | 67,817 | 67,266 | 66,540 | 66,033 | 65,968 | 65,343 | ||||||||||||||||||||||||||||||||||||||||
Liabilities and common shareholders' equity | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Current liabilities: | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Accounts payable and other current liabilities (Note 12) | 4,324 | 3,735 | 3,699 | 3,930 | 3,995 | 3,714 | 3,560 | 3,801 | 3,580 | 3,504 | 3,617 | 4,034 | ||||||||||||||||||||||||||||||||||||||||
Debt due within one year (Note 14) | 1,288 | 867 | 1,521 | 2,522 | 2,227 | 1,652 | 727 | 733 | 1,724 | 1,745 | 2,592 | 1,678 | ||||||||||||||||||||||||||||||||||||||||
Total current liabilities | 5,612 | 4,602 | 5,220 | 6,452 | 6,222 | 5,366 | 4,287 | 4,534 | 5,304 | 5,249 | 6,209 | 5,712 | ||||||||||||||||||||||||||||||||||||||||
Debt due after one year (Note 14) | 29,039 | 29,784 | 30,286 | 30,291 | 30,615 | 29,761 | 31,165 | 31,195 | 31,153 | 31,557 | 31,192 | 31,744 | ||||||||||||||||||||||||||||||||||||||||
Operating lease liabilities | 609 | 619 | 764 | 831 | 758 | 934 | 988 | 1,016 | 1,244 | 1,217 | 1,233 | 1,303 | ||||||||||||||||||||||||||||||||||||||||
Deferred income taxes | 13,525 | 13,475 | 13,329 | 13,029 | 13,144 | 13,199 | 13,166 | 13,146 | 13,095 | 13,069 | 13,084 | 12,868 | ||||||||||||||||||||||||||||||||||||||||
Other long-term liabilities | 1,753 | 1,746 | 1,744 | 1,715 | 1,714 | 1,726 | 1,722 | 1,710 | 1,740 | 1,747 | 1,796 | 1,973 | ||||||||||||||||||||||||||||||||||||||||
Total liabilities | 50,538 | 50,226 | 51,343 | 52,318 | 52,453 | 50,986 | 51,328 | 51,601 | 52,536 | 52,839 | 53,514 | 53,600 | ||||||||||||||||||||||||||||||||||||||||
Common shareholders' equity: | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Common shares, $2.50 par value, 1,400,000,000 authorized; 1,113,359,575 and 1,113,161,191 issued; 593,957,035 and 593,245,884 outstanding, respectively | 2,783 | 2,783 | 2,783 | 2,783 | 2,783 | 2,783 | 2,783 | 2,783 | 2,782 | 2,782 | 2,782 | 2,782 | ||||||||||||||||||||||||||||||||||||||||
Paid-in-surplus | 5,677 | 5,621 | 5,548 | 5,505 | 5,075 | 5,297 | 5,249 | 5,213 | 5,166 | 5,128 | 5,099 | 5,055 | ||||||||||||||||||||||||||||||||||||||||
Retained earnings | 71,584 | 70,411 | 68,501 | 67,532 | 66,450 | 64,677 | 63,820 | 62,940 | 61,235 | 60,500 | 59,724 | 58,047 | ||||||||||||||||||||||||||||||||||||||||
Treasury stock | 58,815 | 58,844 | 58,856 | 58,870 | 57,549 | 55,481 | 54,757 | 54,661 | 54,682 | 54,699 | 54,591 | 53,309 | ||||||||||||||||||||||||||||||||||||||||
Accumulated other comprehensive loss (Note 9) | (556) | (553) | (672) | (692) | (720) | (692) | (606) | (610) | (497) | (517) | (560) | (832) | ||||||||||||||||||||||||||||||||||||||||
Total common shareholders' equity | 20,673 | 19,418 | 17,304 | 16,258 | 16,039 | 16,584 | 16,489 | 15,665 | 14,004 | 13,194 | 12,454 | 11,743 | ||||||||||||||||||||||||||||||||||||||||
Total liabilities and common shareholders' equity | $ 71,211 | $ 69,644 | $ 68,647 | $ 68,576 | $ 68,492 | $ 67,570 | $ 67,817 | $ 67,266 | $ 66,540 | $ 66,033 | $ 65,968 | $ 65,343 |