Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Millions				3 Months Ended		9 Months Ended
	Oct. 14, 2016	Aug. 31, 2016	Aug. 30, 2016	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Feb. 25, 2016
Common stock dividends paid						$ 156.7	$ 147.3
Dividends declared per common share (in dollars per share)		$ 2.52	$ 2.20	$ 0.63	$ 0.55	$ 1.73	$ 1.65
Stock repurchase program, authorized amount								$ 200.0
Repurchases of common stock						$ 100.3	$ 98.1
Shares of common stock repurchased						1,987,187
Subsequent Event
Common stock dividends paid	$ 59.4
Dividends paid per common share (in dollars per share)	$ 0.63