Stockholders' Investment (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance		$ 556,439	$ 524,287
Net Income	[1],[2]	900	9,820
Share-based compensation	[2]	549	796
Issuance of restricted stock units, net of taxes paid		(164)	(839)
Issuance of common stock from stock options		0	2,178
(Tax deficiency) excess tax benefit on share-based compensation		(253)	811
Ending balance		$ 557,471	$ 537,053

[1] See Note 13 “Restatement of Previously Issued Financial Statements

[2] See Note 13 “Restatement of Previously Issued Financial Statements.”