Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating Activities
Net income	$ 5,990	$ 5,161	$ 5,481
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	2,456	2,476	2,403
Deferred income taxes	446	289	553
Long-term casualty and environmental liabilities, net	9	(19)	(49)
Other, net	(2,644)	(108)	(351)
Changes in current assets and liabilities:
Accounts receivable, net	(73)	122	134
Materials and supplies	(61)	(14)	4
Other current assets	50	20	(110)
Accounts payable and other current liabilities	336	(27)	122
Net cash provided by operating activities	6,509	7,900	8,187
Investing Activities
Capital expenditures excluding equipment	(2,735)	(2,819)	(3,193)
Acquisition of equipment	(174)	(244)	(415)
Purchases of investments and investments in time deposits	0	0	(6)
Proceeds from sales of investments and maturities of time deposits	1	32	42
Other, net	(17)	(32)	(170)
Net cash used for investing activities	(2,925)	(3,063)	(3,742)
Financing Activities
Proceeds from issuance of long-term debt	1,550	575	825
Payments on long-term debt and finance leases	(1,543)	(570)	(833)
Cash distributions	(3,800)	(4,830)	(4,425)
Other, net	(19)	(10)	(13)
Net cash used for financing activities	(3,812)	(4,835)	(4,446)
Increase (decrease) in cash and cash equivalents	(228)	2	(1)
Cash and cash equivalents:
Beginning of period	1,986	1,984	1,985
End of period	1,758	1,986	1,984
Supplemental Cash Flow Information
Interest paid, net of amounts capitalized	1,032	1,045	1,064
Capital investments accrued but not yet paid	238	156	245
Income taxes paid, net of refunds	1,386	1,278	1,196
Non-cash asset financing	$ 16	$ 19	$ 11