Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net Income	$ 48,763	$ 30,671	$ 96,965
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustment, net of tax of ($348), $266 and $132 for the years ended December 31, 2016, 2015 and 2014	569	(434)	(216)
Unrealized (loss) gain on available-for-sale securities, net of tax of ($32), $71, and ($76) for the years ended December 31, 2016, 2015 and 2014, respectively	241	(358)	124
Other comprehensive (loss) income	810	(792)	(92)
Comprehensive income	49,573	29,879	96,873
Comprehensive (income) loss attributable to noncontrolling interests	(261)	4,435	735
Comprehensive income attributable to common stockholders	$ 49,312	$ 34,314	$ 97,608