Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Net Income	$ 96,965	$ 77,130	$ 37,773
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustment, net of tax of $132 and ($50) for the years ended December 31, 2014 and 2013	(216)	81
Unrealized gain (loss) on available-for-sale securities, net of tax of ($76), $223, and $81 for the years ended December 31, 2014, 2013 and 2012, respectively	124	56	(273)
Other comprehensive (loss) income	(92)	137	(273)
Comprehensive income	96,873	77,267	37,500
Comprehensive income attributable to noncontrolling interests	735	(1,940)	(101)
Allocation of comprehensive income to preferred stockholders	0		(64)
Comprehensive income attributable to common stockholders	$ 97,608	$ 75,327	$ 37,335