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, 2014	$ 411	$ (43,598)	$ 320,084	$ 29,384	$ 15,112	$ 321,393
BALANCE (in shares) at Dec. 31, 2014	41,123,365
BALANCE (in shares) at Dec. 31, 2014		3,853,586
Increase (Decrease) in Stockholders' Equity
Net income						$ 42,557
BALANCE (in shares) at Sep. 30, 2015						37,486,000
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
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:
Excersied (in shares)		(317,333)
Issuance of shares for options exercised including tax benefit		$ 3,728	966			4,694
Issuance of shares for options exercised including tax benefit (in shares)		317,333
Issuance of restricted stock			(626)			1,666
Issuance of restricted stock & performance stock		$ 2,292
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
BALANCE (in shares) at Dec. 31, 2015		3,696,781				(3,696,781)
Increase (Decrease) in Stockholders' Equity
Net income				48,029		$ 48,029
Issuance of Stock:
Issuance of shares for options exercised (unaudited)		$ 765	(32)			733
Excersied (in shares)		(56,999)
Stock Issued During Period, Value, Stock Options Exercised		$ 765	(32)			733
Issuance of shares for options exercised including tax benefit (in shares)		56,999
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			3,024			3,024
Dividends				(7,663)		(7,663)
Share repurchase		$ (10,977)				(10,977)
Share repurchase (in shares)		(384,286)
Acquisition of noncontrolling interests			(15,521)		$ (18,284)	(33,805)
BALANCE at Sep. 30, 2016	$ 411	$ (56,079)	$ 310,930	109,718		$ 364,980
BALANCE (in shares) at Sep. 30, 2016	41,123,365					37,230,000
BALANCE (in shares) at Sep. 30, 2016		3,893,129				(3,893,129)
Increase (Decrease) in Stockholders' Equity
Cumulative effect of change in accounting principle (unaudited)				$ (38)		$ (38)