Equity (Details) (USD $)	0 Months Ended		1 Months Ended	3 Months Ended	4 Months Ended	12 Months Ended			1 Months Ended			0 Months Ended
	Jul. 25, 2013	Apr. 02, 2013	Dec. 31, 2013	Mar. 31, 2013	Jul. 25, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Feb. 28, 2012	Dec. 31, 2011	Apr. 30, 2012	Jun. 25, 2014	Feb. 12, 2015	Mar. 25, 2013	Dec. 04, 2013
Dividend history
Quarterly dividend rate (in usd per share)						$ 0.30	$ 0.28	$ 0.255
Annualized dividend rate (in usd per share)						$ 1.2	$ 1.12	$ 1.02
Special dividend (in dollars per share)						$ 0	$ 0	$ 2.50
Dividends paid						$ 326,000,000	$ 308,000,000	$ 984,000,000
Share repurchases
Average price paid per share (in dollars per share)			$ 58.36			$ 79.06	$ 58.52	$ 50.35
Total cash utilized						346,000,000	989,000,000	298,000,000
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Balance as of December 31, 2013			810,000,000			810,000,000	810,000,000
Net income attributable to noncontrolling interest						92,000,000
Distributions to noncontrolling interest						(91,000,000)	(22,000,000)	(223,000,000)
Redemption value adjustment						(1,000,000)
Balance as of December 31, 2014			810,000,000			810,000,000	810,000,000
Stockholders' Equity Note [Abstract]
Preferred stock authorized (shares)						2,000,000
Preferred stock issued (in shares)						0
Par value of Preferred stock (in usd per share)						$ 1
Quarterly dividend rate (in usd per share)						$ 0.30	$ 0.28	$ 0.255
Authorized amount														500,000,000
Shares repurchased (in shares)	700,000	1,400,000		7,200,000	9,300,000
Volume weighted-average share price (in dollars per share)	$ 53.7995				$ 53.7995
Average price paid per share (in dollars per share)			$ 58.36			$ 79.06	$ 58.52	$ 50.35
Interest in joint venture minimum percentage						20.00%
Change in control period						15 days
2013 Repurchase Program [Member]
Share repurchases
Total number of shares purchased (in shares)						4,400,000	0	0
Stockholders' Equity Note [Abstract]
Stock repurchase program number of shares authorized to be repurchased (shares)															50,000,000
Maximum number of shares authorized for repurchase under stock repurchase plan as percentage of outstanding common stock															18.00%
Remaining shares available under repurchase program						45,600,000.0
2011 Repurchase Program [Member]
Share repurchases
Total number of shares purchased (in shares)						0	16,900,000	6,800,000
Stockholders' Equity Note [Abstract]
Stock repurchase program number of shares authorized to be repurchased (shares)										50,000,000
Maximum number of shares authorized for repurchase under stock repurchase plan as percentage of outstanding common stock										17.00%
Remaining shares available under repurchase program						0
Number of agreements entered								2
Authorized amount										500,000,000
Shares repurchased (in shares)			100,000
Shares repurchased value			10,000,000
Stock Repurchases [Member]
Share repurchases
Total cash utilized			362,000,000			352,000,000	989,000,000	295,000,000
Uncollared ASR Agreement [Member]
Stockholders' Equity Note [Abstract]
Authorized amount										250,000,000
Shares repurchased (in shares)									800,000	5,000,000
Capped ASR Agreement [Member]
Stockholders' Equity Note [Abstract]
Authorized amount										250,000,000
Shares repurchased (in shares)										5,000,000	100,000
Harold W. McGraw III [Member]
Share repurchases
Total number of shares purchased (in shares)												500,000
Repurchase discount												0.35%
Average price paid per share (in dollars per share)												$ 82.66
Total cash utilized												$ 41,000,000
Stockholders' Equity Note [Abstract]
Average price paid per share (in dollars per share)												$ 82.66
Subsequent Event [Member]
Dividend history
Quarterly dividend rate (in usd per share)													$ 0.33
Stockholders' Equity Note [Abstract]
Quarterly dividend rate (in usd per share)													$ 0.33