Condensed Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interest
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Jun. 30, 2015	$ 284,554	$ 279	$ 123,038	$ 194,394	$ (18,489)	$ (5,926)	$ (8,742)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Noncontrolling Interest, Increase from Subsidiary Equity Issuance	8,433						8,433
Net income	12,857			15,372			(2,515)
Other comprehensive income (loss)	(3,815)					(3,815)
Treasury shares sold to Employee Stock Purchase Plan	166		89		77
Exercise of stock options	457		(7)		464
Issuance of deferred shares	0		(5,706)		5,706
Other treasury share purchases	(4,488)				(4,488)
Tax effect of exercised stock options and vesting of deferred shares	3,245		3,245
Stock-based compensation expense	3,509		3,509
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Dec. 31, 2015	304,918	279	124,168	209,766	(16,730)	(9,741)	(2,824)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning equity balances, as adjusted	315,566	279	127,058	223,157	(26,907)	(6,845)	(1,176)
Retrospective adjustment upon adoption of ASU 2016-09 (see Note 1)	0		100	(100)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Jun. 30, 2016	315,566	279	126,958	223,257	(26,907)	(6,845)	(1,176)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	14,592			14,592			0
Other comprehensive income (loss)	(1,997)					(1,997)
Treasury shares sold to Employee Stock Purchase Plan	169		12		157
Exercise of stock options	222		(273)		495
Issuance of deferred shares	0		(5,685)		5,685
Other treasury share purchases	(2,270)				(2,270)
Stock-based compensation expense	3,547		3,547
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest at Dec. 31, 2016	$ 329,829	$ 279	$ 124,659	$ 237,749	$ (22,840)	$ (8,842)	$ (1,176)