Share Repurchase Program (Details) - USD ($) $ / shares in Units, shares in Thousands	2 Months Ended	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2018	Mar. 31, 2017	Jan. 23, 2018
Equity [Abstract]
Authorized amount				$ 150,000,000
Value repurchased	$ 26,700,000	$ 26,733,000	$ 15,151,000
Shares repurchased (in shares)	535
Shares repurchased, average cost per share (in dollars per share)	$ 49.98