Capital Stock - Additional Information (Details) - USD ($)	1 Months Ended	12 Months Ended
	Oct. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Jun. 30, 2014	Jul. 31, 2013
Equity Class Of Treasury Stock [Line Items]
Total cost of shares repurchased		$ 146,100,000	$ 160,000,000	$ 90,000,000
2015 Repurchase Plan
Equity Class Of Treasury Stock [Line Items]
Additional authorized amount of outstanding common stock to be repurchased	$ 250,000,000
Total cost of shares repurchased		46,100,000
2014 Repurchase Plan
Equity Class Of Treasury Stock [Line Items]
Total cost of shares repurchased		$ 100,000,000
Authorized amount to repurchase outstanding common stock					$ 150,000,000
2013 Repurchase Plan
Equity Class Of Treasury Stock [Line Items]
Authorized amount to repurchase outstanding common stock						$ 150,000,000