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 Income (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 4)	151					151
Comprehensive income (loss)	38,972				(1,707)	40,679
Issuances of common stock	2,174	$ 1		2,173
Issuances of common stock, shares		148
Vesting of restricted stock and restricted stock units, net of forfeitures and tax withholdings	(5,048)			(5,048)
Vesting of restricted stock and restricted stock units, net of forfeitures and tax withholdings, shares		482
Share-based compensation expense	5,466			5,466
Repurchases of common stock	(18,847)		$ (18,847)
Repurchases of common stock, shares			(911)
Balance at Jun. 30, 2018	710,202	$ 59	$ (243,213)	662,416	(20,885)	311,825
Balance, shares at Jun. 30, 2018		58,677	(13,572)
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)
Comprehensive income (loss)	25,493				(3,333)	28,826
Issuances of common stock	936	$ 1		935
Issuances of common stock, shares		59
Vesting of restricted stock and restricted stock units, net of forfeitures and tax withholdings	(3,532)			(3,532)
Vesting of restricted stock and restricted stock units, net of forfeitures and tax withholdings, shares		388
Share-based compensation expense	2,089			2,089
Repurchases of common stock	(7,490)		$ (7,490)
Repurchases of common stock, shares			(342)
Balance at Jun. 30, 2018	710,202	$ 59	$ (243,213)	662,416	(20,885)	311,825
Balance, shares at Jun. 30, 2018		58,677	(13,572)
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 income (loss)	18,367				600	13,360	4,407
Dividends paid	(3,920)					(3,920)
Issuances of common stock	1,464			1,464
Issuances of common stock, shares		98
Vesting of restricted stock and restricted stock units, net of forfeitures and tax withholdings	(3,846)	$ 1		(3,847)
Vesting of restricted stock and restricted stock units, net of forfeitures and tax withholdings, shares		392
Share-based compensation expense	6,981			6,981
Additional paid-in capital recorded through compensation expense	2,082			2,082
Repurchases of common stock	(74,244)		$ (74,244)
Repurchases of common stock, shares			(3,300)
Balance at Jun. 30, 2019	655,837	$ 50	$ (235,216)	671,153	(5,929)	220,983	4,796
Balance, shares at Jun. 30, 2019		49,877	(11,414)
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)
Comprehensive income (loss)	12,490				1,042	9,079	2,369
Dividends paid	(1,926)					(1,926)
Issuances of common stock	608			608
Issuances of common stock, shares		29
Vesting of restricted stock and restricted stock units, net of forfeitures and tax withholdings	(2,542)	$ 1		(2,543)
Vesting of restricted stock and restricted stock units, net of forfeitures and tax withholdings, shares		302
Share-based compensation expense	4,212			4,212
Additional paid-in capital recorded through compensation expense	2,082			2,082
Repurchases of common stock	(20,751)		$ (20,751)
Repurchases of common stock, shares			(983)
Balance at Jun. 30, 2019	$ 655,837	$ 50	$ (235,216)	$ 671,153	$ (5,929)	$ 220,983	$ 4,796
Balance, shares at Jun. 30, 2019		49,877	(11,414)