CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock	Treasury Stock	Additional Paid-In Capital	Retained Earnings	Non-Controlling Interests	Total
BALANCE at Dec. 31, 2013	$ 411	$ (37,468)	$ 318,123	$ 14,768	$ 18,188	$ 314,022
BALANCE (in shares) at Dec. 31, 2013	41,123,365
BALANCE (in shares) at Dec. 31, 2013		3,488,438
Increase (Decrease) in Stockholders' Equity
Net income				23,063	5,536	28,599
Issuance of Stock:
Issuance of shares for options exercised		$ 1,132	79			1,211
Issuance of shares for options exercised including tax benefit (in shares)		103,619
Issuance of restricted stock		$ 1,243	(1,243)
Issuance of restricted stock (in shares)		115,044
Shares received in lieu of tax withholding payment on vested restricted stock		$ (531)				(531)
Shares received in lieu of tax withholding payment on vested restricted stock (in shares)		(34,657)
Tax benefit from vesting of restricted stock			133			133
Stock-based compensation			2,992			2,992
Dividends				(8,447)		(8,447)
Distribution to noncontrolling interests					(8,612)	(8,612)
Share repurchase		$ (7,974)				(7,974)
Share repurchase (in shares)		(549,154)
BALANCE at Dec. 31, 2014	$ 411	$ (43,598)	320,084	29,384	15,112	$ 321,393
BALANCE (in shares) at Dec. 31, 2014	41,123,365					37,270,000
BALANCE (in shares) at Dec. 31, 2014		3,853,586
Increase (Decrease) in Stockholders' Equity
Net income				49,364	8,076	$ 57,440
Issuance of Stock:
Issuance of shares for options exercised		$ 3,728	966			4,694
Issuance of shares for options exercised including tax benefit (in shares)		317,333
Issuance of restricted stock & performance stock		$ 2,292	(626)			1,666
Issuance of restricted stock & performance stock (in shares)		200,015
Shares received in lieu of tax withholding payment on vested restricted stock		$ (937)				(937)
Shares received in lieu of tax withholding payment on vested restricted stock (in shares)		(44,590)
Tax benefit from vesting of restricted stock			284			284
Stock-based compensation			3,057			3,057
Dividends				(9,358)		(9,358)
Distribution to noncontrolling interests					(4,904)	(4,904)
Share repurchase		$ (8,330)				(8,330)
Share repurchase (in shares)		(315,953)
BALANCE at Dec. 31, 2015	$ 411	$ (46,845)	323,765	69,390	18,284	$ 365,005
BALANCE (in shares) at Dec. 31, 2015	41,123,365					37,427,000
BALANCE (in shares) at Dec. 31, 2015		3,696,781				(3,696,781)
Increase (Decrease) in Stockholders' Equity
Net income				64,896		$ 64,896
Issuance of Stock:
Issuance of shares for options exercised		$ 1,568	10			1,578
Issuance of shares for options exercised including tax benefit (in shares)		111,761
Issuance of restricted stock & performance stock		$ 2,282	(306)			1,976
Issuance of restricted stock & performance stock (in shares)		172,727
Shares received in lieu of tax withholding payment on vested restricted stock		$ (1,304)				(1,304)
Shares received in lieu of tax withholding payment on vested restricted stock (in shares)		(41,788)
Stock-based compensation			3,502			3,502
Dividends				(10,264)		(10,264)
Share repurchase		$ (13,088)				(13,088)
Share repurchase (in shares)		(460,170)
Acquisition of noncontrolling interests			(17,346)		$ (18,284)	(35,630)
BALANCE at Dec. 31, 2016	$ 411	$ (57,387)	$ 309,625	123,984		$ 376,633
BALANCE (in shares) at Dec. 31, 2016	41,123,365					37,209,000
BALANCE (in shares) at Dec. 31, 2016		3,914,251				(3,914,251)
Increase (Decrease) in Stockholders' Equity
Cumulative effect of change in accounting principle (unaudited)				$ (38)		$ (38)