CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock	Retained Earnings	Accumulated Other Comprehensive (Loss) Income	Treasury Stock	Non-controlling Interest	Total
Beginning Balance (in shares) at Dec. 31, 2017	65,897,866
Beginning Balance at Dec. 31, 2017	$ 424,694	$ 154,324	$ (1,461)		$ 15,027	$ 592,584
Increase (Decrease) in Stockholders' Equity
Allocation of ownership interest	(490)				490
Additional ownership interest	297				(297)
Capital contribution from non-controlling interest					887	887
Capital distribution to non-controlling interest					(200)	(200)
Stock based compensation expense	$ 57					57
Stock based compensation expense (in shares)	2,778
Issuance of common stock for officer compensation, net of tax withholding	$ 192					192
Issuance of common stock for officer compensation, net of tax withholding (in shares)	9,956
Repurchase of common shares				$ (93,369)		(93,369)
Repurchase of common shares (in shares)	(5,238,566)
Retirement of treasury stock	$ (93,369)			93,369
Adoption of ASU 2018-02 Income Statement - Reporting Comprehensive Income		313	(313)
Other comprehensive income (loss)						1,159
Other comprehensive (loss) income, net of tax, excluding adoption of ASUs			776			776
Net income		32,435			(400)	32,035
Ending Balance at Sep. 30, 2018	$ 331,381	187,516	(302)		15,507	534,102
Ending Balance (in shares) at Sep. 30, 2018	60,672,034
Beginning Balance (in shares) at Jun. 30, 2018	61,842,662
Beginning Balance at Jun. 30, 2018	$ 424,736	182,033	(613)	(72,463)	15,847	549,540
Increase (Decrease) in Stockholders' Equity
Capital distribution to non-controlling interest					(201)	(201)
Stock based compensation expense	$ 14					14
Stock based compensation expense (in shares)	2,778
Repurchase of common shares				(20,906)		(20,906)
Repurchase of common shares (in shares)	(1,173,406)
Retirement of treasury stock	$ (93,369)			93,369
Other comprehensive income (loss)			311			311
Net income		5,483			(139)	5,344
Ending Balance at Sep. 30, 2018	$ 331,381	187,516	(302)		15,507	534,102
Ending Balance (in shares) at Sep. 30, 2018	60,672,034
Increase (Decrease) in Stockholders' Equity
Adoption of ASU, net of tax | ASU 2014-09		1,140				$ 1,140
Adoption of ASU, net of tax | ASU 2016-01		(696)	696
Beginning Balance (in shares) at Dec. 31, 2018	60,672,034					60,672,034
Beginning Balance at Dec. 31, 2018	$ 331,395	187,450	(674)		14,940	$ 533,111
Increase (Decrease) in Stockholders' Equity
Allocation of ownership interest	(1,209)				1,209
Additional ownership interest	(3,787)				(7,832)	(11,619)
Capital contribution from non-controlling interest					1,784	1,784
Capital distribution to non-controlling interest					(200)	(200)
Stock based compensation expense	$ 50					50
Stock based compensation expense (in shares)	5,708
Repurchase of common shares				(18,794)		(18,794)
Repurchase of common shares (in shares)	(1,141,529)
Other comprehensive income (loss)			184			184
Net income		18,087			(53)	18,034
Ending Balance at Sep. 30, 2019	$ 326,449	205,537	(490)	(18,794)	9,848	$ 522,550
Ending Balance (in shares) at Sep. 30, 2019	59,536,213					59,536,213
Beginning Balance (in shares) at Jun. 30, 2019	60,200,534
Beginning Balance at Jun. 30, 2019	$ 330,209	199,820	(70)	(7,073)	19,254	$ 542,140
Increase (Decrease) in Stockholders' Equity
Additional ownership interest	(3,787)				(7,832)	(11,619)
Capital contribution from non-controlling interest					(1,683)	(1,683)
Stock based compensation expense	$ 27					27
Stock based compensation expense (in shares)	5,708
Repurchase of common shares				(11,721)		(11,721)
Repurchase of common shares (in shares)	(670,029)
Other comprehensive income (loss)			(420)			(420)
Net income		5,717			109	5,826
Ending Balance at Sep. 30, 2019	$ 326,449	$ 205,537	$ (490)	$ (18,794)	$ 9,848	$ 522,550
Ending Balance (in shares) at Sep. 30, 2019	59,536,213					59,536,213