Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Activities
Net income	$ 5,161	$ 5,481	$ 5,219
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	2,476	2,403	2,317
Deferred income taxes	289	553	381
Long-term casualty and environmental liabilities, net	(19)	(49)	(18)
Other, net	(108)	(351)	(147)
Changes in current assets and liabilities:
Accounts receivable, net	122	134	(48)
Materials and supplies	(14)	4	10
Other current assets	20	(110)	(52)
Accounts payable and other current liabilities	(27)	122	246
Net cash provided by operating activities	7,900	8,187	7,908
Investing Activities
Capital expenditures excluding equipment	(2,819)	(3,193)	(2,918)
Acquisition of equipment	(244)	(415)	(269)
Purchases of investments and investments in time deposits	0	(6)	(27)
Proceeds from sales of investments and maturities of time deposits	32	42	45
Other, net	(32)	(170)	(11)
Net cash used for investing activities	(3,063)	(3,742)	(3,180)
Financing Activities
Proceeds from issuance of long-term debt	575	825	1,500
Payments on long-term debt and finance leases	(570)	(833)	(746)
Cash distributions	(4,830)	(4,425)	(5,450)
Other, net	(10)	(13)	(22)
Net cash used for financing activities	(4,835)	(4,446)	(4,718)
Increase (decrease) in cash and cash equivalents	2	(1)	10
Cash and cash equivalents:
Beginning of period	1,984	1,985	1,975
End of period	1,986	1,984	1,985
Supplemental Cash Flow Information
Interest paid, net of amounts capitalized	1,045	1,064	1,072
Capital investments accrued but not yet paid	156	245	251
Income taxes paid, net of refunds	1,278	1,196	905
Non-cash asset financing	$ 19	$ 11	$ 8