Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Statement of Comprehensive Income [Abstract]
Net Income	$ 11,870	$ 19,725
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustment, net of tax of ($61) and $165 for the three months ended March 31, 2016 and 2015, respectively	99	(271)
Unrealized gain on available-for-sale securities, net of tax of ($97) and ($1) for the three months ended March 31, 2016 and 2015, respectively	160	4
Other comprehensive income (loss)	259	(267)
Comprehensive income	12,129	19,458
Comprehensive loss (income) attributable to noncontrolling interests	493	(383)
Comprehensive Income Attributable to Common Stockholders	$ 12,622	$ 19,075