Capital Stock - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Feb. 09, 2017	Oct. 31, 2015	Jun. 30, 2014	Jul. 31, 2013
Equity Class Of Treasury Stock [Line Items]
Total cost of shares repurchased	$ 111,100,000	$ 146,100,000	$ 160,000,000
Subsequent event
Equity Class Of Treasury Stock [Line Items]
Authorized amount to repurchase outstanding common stock				$ 300,000,000
2015 Repurchase Plan
Equity Class Of Treasury Stock [Line Items]
Authorized amount to repurchase outstanding common stock					$ 250,000,000
Total cost of shares repurchased	157,200,000
2014 Repurchase Plan
Equity Class Of Treasury Stock [Line Items]
Authorized amount to repurchase outstanding common stock						$ 150,000,000
Total cost of shares repurchased	$ 100,000,000
2013 Repurchase Plan
Equity Class Of Treasury Stock [Line Items]
Authorized amount to repurchase outstanding common stock							$ 150,000,000