Share Repurchases (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Feb. 28, 2018
Equity, Class of Treasury Stock [Line Items]
Common stock authorized for repurchase	$ 8,900
Number of common stock repurchased (in shares)	450,000	119,007
Value of common stock repurchased	$ 11,050	$ 1,821
Maximum
Equity, Class of Treasury Stock [Line Items]
Common stock authorized for repurchase			$ 20,000