Stock Repurchase (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	1 Months Ended	12 Months Ended
	Jan. 31, 2017	Dec. 31, 2015	Dec. 31, 2014
Common stock repurchased (in shares)		1.3	0.7
Common stock repurchased, value		$ 18.7	$ 8.4
Weighted average price per share of common stock (in dollars per share)		$ 14.98	$ 12.54
Subsequent event
Common stock authorized for repurchase, maximum (in shares)	100.0
Stock repurchase program year	3 years