Condensed Consolidated Statements of Cash Flows (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Operating Activities
Net income	$ 1,151	$ 1,088
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation	491	464
Deferred income taxes and unrecognized tax benefits	108	75
Other operating activities, net	32	(57)
Changes in current assets and liabilities:
Accounts receivable, net	47	(128)
Materials and supplies	(32)	(52)
Other current assets	(75)	(93)
Accounts payable and other current liabilities	(155)	84
Income and other taxes	497	386
Cash provided by operating activities	2,064	1,767
Investing Activities
Capital investments	(1,101)	(893)
Proceeds from asset sales	32	27
Other investing activities, net	(73)	(39)
Cash used in investing activities	(1,142)	(905)
Financing Activities
Debt issued (Note 15)	1,146	995
Dividends paid (Note 13)	(922)	(363)
Common share repurchases (Note 18)	(792)	(644)
Debt repaid	(333)	(402)
Other financing activities, net	(20)	(23)
Cash used in financing activities	(921)	(437)
Net change in cash and cash equivalents	1	425
Cash and cash equivalents at beginning of year	1,586	1,432
Cash and cash equivalents at end of period	1,587	1,857
Non-cash investing and financing activities:
Capital investments accrued but not yet paid	146	109
Common shares repurchased but not yet paid	15	39
Cash dividends declared but not yet paid (Note 13)		407
Cash paid for:
Income taxes, net of refunds	(47)	(146)
Interest, net of amounts capitalized	$ (192)	$ (178)