Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Millions			3 Months Ended		6 Months Ended
	Jul. 15, 2016	Feb. 25, 2016	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Common stock dividends paid					$ 104.9	$ 93.5
Dividends declared per common share (in dollars per share)		$ 0.55	$ 0.55	$ 0.55	$ 1.10	$ 1.10
Stock Repurchase Program, Authorized Amount		$ 200.0
Repurchases of common stock					$ 100.3	$ 43.3
Shares of common stock repurchased					1,987,187
Subsequent Event
Common stock dividends paid	$ 51.8