Consolidated Statements of Cash Flows (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
OPERATING ACTIVITIES
Net income	$ 2,675	$ 2,671
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	1,569	1,465
Deferred income taxes	262	457
Long-term casualty and environmental liabilities, net	(20)	(7)
Contribution to defined benefit pension plan	0	(25)
Other, net	(294)	(47)
Changes in current assets and liabilities:
Accounts receivable, net	(73)	(143)
Materials and supplies	(11)	0
Other current assets	(83)	(72)
Accounts payable and other current liabilities	207	(157)
Net cash provided by operating activities	4,232	4,142
INVESTING ACTIVITIES
Capital expenditures excluding equipment	(2,612)	(2,174)
Acquisition of equipment	(1,043)	(640)
Other, net	60	14
Net cash used for investing activities	(3,595)	(2,800)
FINANCING ACTIVITIES
Proceeds from issuance of long-term debt	3,000	3,000
Payments on long-term debt	(611)	(399)
Cash distributions	(2,750)	(2,900)
Other, net	(31)	(28)
Net cash used for financing activities	(392)	(327)
Increase in cash and cash equivalents	245	1,015
Cash and cash equivalents:
Beginning of period	2,225	1,794
End of period	2,470	2,809
SUPPLEMENTAL CASH FLOW INFORMATION
Interest paid, net of amounts capitalized	675	622
Capital investments accrued but not yet paid	329	144
Income taxes paid, net of refunds	$ 1,301	$ 1,198