Consolidated Statements of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
OPERATING ACTIVITIES
Net income	$ 1,556	$ 2,008
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	1,050	985
Deferred income taxes	680	285
Long-term casualty and environmental liabilities, net	(21)	(17)
Other, net	(81)	(24)
Changes in current assets and liabilities:
Accounts receivable, net	34	107
Materials and supplies	(1)	(57)
Other current assets	(155)	(108)
Accounts payable and other current liabilities	(95)	181
Net cash provided by operating activities	2,967	3,360
INVESTING ACTIVITIES
Capital expenditures excluding equipment	(1,542)	(1,952)
Acquisition of equipment	(457)	(522)
Purchases of investments and investments in time deposits	(4)	(123)
Proceeds from sales of investments and maturities of time deposits	10	0
Other, net	(281)	(79)
Net cash used for investing activities	(2,274)	(2,676)
FINANCING ACTIVITIES
Proceeds from issuance of long-term debt	750	2,000
Payments on long-term debt	(252)	(321)
Cash distributions	(1,250)	(2,000)
Other, net	(12)	(19)
Net cash (used for) provided by financing activities	(764)	(340)
(Decrease) increase in cash and cash equivalents	(71)	344
Cash and cash equivalents:
Beginning of period	2,329	2,384
End of period	2,258	2,728
SUPPLEMENTAL CASH FLOW INFORMATION
Interest paid, net of amounts capitalized	516	460
Capital investments accrued but not yet paid	122	214
Income taxes paid, net of refunds	$ 226	$ 548