Equity (Details 3) (USD $)	0 Months Ended	3 Months Ended								12 Months Ended				0 Months Ended
	Jan. 30, 2013	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Previous share repurchase plan	Jan. 29, 2014 Subsequent event
Stock repurchases
Amount authorized under new share repurchase plan	$ 250,000,000.0
Shares available under existing share repurchase plan	715,700
Aggregate repurchase price of common stock										252,600,000	73,700,000	135,400,000
Common stock repurchased (in shares)										3,400,000	1,300,000	3,000,000	2,600,000
Amount of share withholdings for option exercises										23,800,000	30,800,000	39,300,000
Common stock held in treasury		53,500,000				51,000,000				53,500,000	51,000,000
Dividends
Cash dividend paid (in dollars per share)		$ 0.30	$ 0.30	$ 0.30	$ 0.30	$ 0.40	$ 0	$ 0	$ 0.40	$ 1.20	$ 0.80	$ 0.70
Total dividend										52,600,000	37,600,000	31,600,000
Aggregate cash dividend paid										$ 51,800,000	$ 36,000,000	$ 31,600,000
Cash dividend declared (in dollars per share)														$ 0.30