Common Stock Repurchase Program Additional Information (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	1 Months Ended	3 Months Ended	9 Months Ended
	Sep. 30, 2016	Oct. 31, 2016	Oct. 31, 2016
Common Stock
Equity, Class of Treasury Stock [Line Items]
Repurchased shares of its common stock on the open market, value		$ 39.9	$ 151.4
Retained Earnings
Equity, Class of Treasury Stock [Line Items]
Repurchased shares of its common stock on the open market, value		$ 99.7	$ 258.2
Common Stock Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Common stock repurchased and retired (in shares)		2.0	6.8
Repurchased shares of its common stock on the open market, average repurchase price per share (in usd per share)		$ 68.74	$ 59.92
Common Stock shares remained available for repurchase under repurchase plans (in shares)		29.5	29.5
Stock Repurchase Program, Shares Authorized During Period	30.0