Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Operating Activities
Net income	$ 1,143	$ 1,247
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	661	647
Deferred income taxes	45	71
Other, net	(64)	(47)
Changes in current assets and liabilities:
Accounts receivable, net	95	(19)
Materials and supplies	20	18
Other current assets	(26)	(35)
Accounts payable and other current liabilities	(183)	(431)
Net cash provided by operating activities	1,691	1,451
Investing Activities
Capital expenditures excluding equipment	(647)	(679)
Acquisition of equipment	(75)	(16)
Purchases of investments and investments in time deposits	(23)	(15)
Other, net	(104)	(134)
Net cash used in investing activities	(849)	(844)
Financing Activities
Payments on long-term debt and finance leases	(6)	(708)
Cash distributions	(500)	0
Net cash used in financing activities	(506)	(708)
Increase (decrease) in cash and cash equivalents	336	(101)
Cash and cash equivalents:
Beginning of period	2,148	1,938
End of period	2,484	1,837
Supplemental Cash Flow Information
Interest paid, net of amounts capitalized	269	300
Capital investments accrued but not yet paid	149	172
Income taxes paid, net of refunds	$ 2	$ 8