Capital Stock (Narrative) (Details) (USD $)	1 Months Ended	12 Months Ended			3 Months Ended	1 Months Ended
	Apr. 30, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jun. 30, 2014	Oct. 31, 2014
Class of Stock [Line Items]
Stock repurchase program, authorized amount	$ 1,500,000,000.0	$ 5,400,000,000.0
Payments for Repurchase of Common Stock		1,640,885,000	406,326,000	251,008,000
Available to repurchase common stock		288,400,000
Amount expended on share repurchases in open market transactions		1,640,885,000	406,326,000	251,008,000
Number of shares repurchased			6,563,986	3,550,817
Average per share price on share repurchases in open market transactions (in dollars per share)			$ 61.90	$ 70.69
Total tax withholdings for share-based compensation (in shares)		560,239	444,657	269,745
Total tax withholdings for share-based compensation		33,672,000	31,013,000	20,170,000
Preferred stock, shares authorized		5,000,000	5,000,000
Preferred stock, par value (in dollars per share)		$ 0.01	$ 0.01
Privately Negotiated Transaction [Member]
Class of Stock [Line Items]
Payments for Repurchase of Common Stock					101,000,000
Number of shares repurchased					1,700,000
Purchase From Accelerated Share Repurchase [Member]
Class of Stock [Line Items]
Number of shares repurchased					21,800,000	2,600,000
Shares repurchased under the ASR					1,400,000,000
Open Market Purchases [Member]
Class of Stock [Line Items]
Amount expended on share repurchases in open market transactions		$ 139,900,000
Number of shares repurchased		2,046,400
Average per share price on share repurchases in open market transactions (in dollars per share)		$ 68.36