Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net Income (Loss)	$ 39,939	$ 48,763	$ 30,671
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustment, net of tax of ($4), ($348) and $266 for the years ended December 31, 2017, 2016 and 2015	12	569	(434)
Unrealized (loss) gain on available-for-sale securities, net of tax of $100, ($32), and $71 for the years ended December 31, 2017, 2016 and 2015, respectively	(388)	241	(358)
Other comprehensive income (loss)	(376)	810	(792)
Comprehensive income (loss)	39,563	49,573	29,879
Comprehensive (income) loss attributable to noncontrolling interests	(2,927)	(261)	4,435
Comprehensive income (loss) attributable to stockholders	$ 36,636	$ 49,312	$ 34,314