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, 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)
Increase (Decrease) in Stockholders' Equity
Net income						$ 27,558
BALANCE (in shares) at Jun. 30, 2016						37,444,000
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)
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 (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)
Stockholders' Equity Attributable to Parent, Ending Balance at Dec. 31, 2016	$ 411	$ (57,387)	309,625	123,984		$ 376,633
BALANCE (in shares) at Dec. 31, 2016	41,123,365
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)
Net income				25,449		25,449
Issuance of Stock:
Issuance of shares for options exercised		$ 1,366	(70)			1,296
Issuance of shares for options exercised (in shares)		90,498
Issuance of restricted stock & performance stock		$ 2,037	(421)			1,616
Issuance of restricted stock & performance stock (in shares)		134,646
Shares received in lieu of tax withholding payment on vested restricted stock		$ (1,419)				(1,419)
Shares received in lieu of tax withholding payment on vested restricted stock (in shares)		(39,335)
Stock-based compensation			2,558			2,558
Dividends				(5,405)		(5,405)
Share repurchase		$ (3,816)				(3,816)
Share repurchase (in shares)		(107,293)
Stockholders' Equity Attributable to Parent, Ending Balance at Jun. 30, 2017	$ 411	$ (59,219)	$ 311,692	$ 144,028		$ 396,912
BALANCE (in shares) at Jun. 30, 2017	41,123,365					37,288,000
BALANCE (in shares) at Jun. 30, 2017		(3,835,735)				3,835,735