Consolidated Statements of Cash Flows (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
OPERATING ACTIVITIES
Net income	$ 3,869	$ 3,793	$ 3,372
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	2,123	1,973	1,889
Deferred income taxes	941	583	660
Long-term casualty and environmental liabilities, net	(43)	(98)	(190)
Contributions to qualified pension plan	0	(25)	(36)
Other, net	(310)	(88)	(314)
Changes in current assets and liabilities:
Accounts receivable, net	(88)	(130)	(6)
Materials and supplies	40	(35)	(61)
Other current assets	(36)	(6)	14
Accounts payable and other current liabilities	85	(205)	105
Net cash provided by operating activities	6,581	5,762	5,433
INVESTING ACTIVITIES
Capital expenditures excluding equipment	(3,734)	(2,975)	(2,596)
Acquisition of equipment	(1,509)	(943)	(952)
Partnership Investment	0	0	(130)
Other, net	(6)	55	(158)
Net cash used for investing activities	(5,249)	(3,863)	(3,836)
FINANCING ACTIVITIES
Proceeds from issuance of long-term debt	3,000	3,000	2,500
Payments on long-term debt	(641)	(440)	(482)
Cash distributions	(3,500)	(4,000)	(3,750)
Other, net	(32)	(28)	(31)
Net cash used for financing activities	(1,173)	(1,468)	(1,763)
Increase/(decrease) in cash and cash equivalents	159	431	(166)
Cash and cash equivalents:
Beginning of period	2,225	1,794	1,960
End of period	2,384	2,225	1,794
SUPPLEMENTAL CASH FLOW INFORMATION
Interest paid, net of amounts capitalized	859	772	707
Capital investments accrued but not yet paid	293	224	123
Income taxes paid, net of refunds	$ 1,366	$ 1,752	$ 1,194