Share Repurchases - Additional Information (Details) - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Nov. 02, 2016
Accelerated Share Repurchases [Line Items]
Stock repurchase program, authorized amount				$ 500.0
Stock purchases, shares	9.0
Payment for share repurchase	$ 400.0	$ 363.1	$ 478.8
Evergreen Program
Accelerated Share Repurchases [Line Items]
Payment for share repurchase	103.0
2015 Repurchase Program
Accelerated Share Repurchases [Line Items]
Payment for share repurchase	97.0
Repurchase Program
Accelerated Share Repurchases [Line Items]
Payment for share repurchase	200.0
Remaining amount for share repurchase program	$ 300.0