Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Retained Earnings [Member]	Non-Controlling Interest [Member]
Balance at Dec. 31, 2017	$ 687,334	$ 58	$ (224,366)	$ 659,825	$ (19,178)	$ 270,995
Balance, shares at Dec. 31, 2017		58,047	(12,661)
Cumulative-effect adjustment resulting from the adoption of ASU 2014-09 (Note 2)	151					151
Comprehensive (loss) income	13,479				1,626	11,853
Issuances of common stock	1,238			1,238
Issuances of common stock, shares		89
Vesting of restricted stock and restricted stock units, net of forfeitures and tax withholdings	(1,516)			(1,516)
Vesting of restricted stock and restricted stock units, net of forfeitures and tax withholdings, shares		94
Share-based compensation expense	3,377			3,377
Repurchases of common stock	(11,357)		$ (11,357)
Repurchases of common stock, shares			(569)
Balance at Mar. 31, 2018	692,706	$ 58	$ (235,723)	662,924	(17,552)	282,999
Balance, shares at Mar. 31, 2018		58,230	(13,230)
Balance at Dec. 31, 2018	712,553	$ 49	$ (160,972)	664,473	(6,529)	211,543	$ 3,989
Balance, shares at Dec. 31, 2018		49,387	(8,114)
Distributions to non-controlling interests	(3,600)						(3,600)
Comprehensive (loss) income	5,877				(442)	4,281	2,038
Dividends paid ($0.05 per share)	(1,994)					(1,994)
Issuances of common stock	856			856
Issuances of common stock, shares		69
Vesting of restricted stock and restricted stock units, net of forfeitures and tax withholdings	(1,304)			(1,304)
Vesting of restricted stock and restricted stock units, net of forfeitures and tax withholdings, shares		90
Share-based compensation expense	2,769			2,769
Repurchases of common stock	(53,493)		$ (53,493)
Repurchases of common stock, shares			(2,317)
Balance at Mar. 31, 2019	$ 661,664	$ 49	$ (214,465)	$ 666,794	$ (6,971)	$ 213,830	$ 2,427
Balance, shares at Mar. 31, 2019		49,546	(10,431)