Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Net Income (Loss)	$ 22,468	$ 23,827
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustment, net of tax of $(3) and ($4) for the three months ended March 31, 2019 and 2018, respectively	6	10
Unrealized gain (loss) on available-for-sale securities, net of tax of $97 for the three months ended March 31, 2018	0	(249)
Other comprehensive income (loss)	6	(239)
Comprehensive income (loss)	22,474	23,588
Comprehensive (income) loss attributable to noncontrolling interests	(722)	(527)
Comprehensive Income (Loss) Attributable to Stockholders	$ 21,752	$ 23,061