Subsequent Events (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions				1 Months Ended	3 Months Ended		6 Months Ended
	Jul. 25, 2017	Apr. 25, 2017	Jan. 26, 2017	Aug. 08, 2017	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Subsequent Event [Line Items]
Cash dividends declared per common stock (in dollars per share)		$ 0.10	$ 0.10		$ 0.10	$ 0.10	$ 0.20	$ 0.20
Subsequent Event
Subsequent Event [Line Items]
Cash dividends declared per common stock (in dollars per share)	$ 0.10
Common Stock | Subsequent Event
Subsequent Event [Line Items]
Stock repurchased during period (in shares)				3.7
Shares repurchased during the period				$ 102.7
Average price per share (in dollars per share)				$ 28.13
Shares settled (in shares)				2.6
Stock repurchase program, remaining authorized repurchase amount				$ 367.0