Stockholders' Equity - Share Repurchase Program (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	21 Months Ended
	Mar. 31, 2016	Mar. 31, 2016	Oct. 31, 2015	Dec. 31, 2014
Stockholders' Equity Note [Abstract]
Amount of shares authorized to be repurchased			$ 335.0	$ 205.0
Amount of additional share repurchases authorized			$ 130.0
Shares repurchased	4,116,271	13,079,057
Cost of shares repurchased	$ 60.9	$ 280.5
Average purchase price	$ 14.80	$ 21.45