Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Millions						3 Months Ended		6 Months Ended
	Aug. 07, 2017	Jun. 22, 2017	May 08, 2017	Mar. 28, 2017	Feb. 28, 2017	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Subsequent Event [Line Items]
Dividends per share (in dollars per share)			$ 0.09		$ 0.09	$ 0.09	$ 0.08	$ 0.18	$ 0.16
Cash payment amount		$ 4.2		$ 4.2				$ 8.4	$ 7.5
Common stock repurchased, number of shares repurchased (in shares)						0	43,682	0	88,916
Common stock repurchased, average price per share (in dollars per share)							$ 40.05		$ 39.36
Common stock repurchased, total repurchase costs							$ 1.7		$ 3.5
Common stock available for future share repurchases, amount						$ 2.6		$ 2.6
Subsequent Event
Subsequent Event [Line Items]
Dividends per share (in dollars per share)	$ 0.09