Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 33,977	$ 25,516	$ 95,528	$ 74,952
Other comprehensive income (loss):
Change in unrealized gains on securities	401	(716)	(438)	624
Increase (decrease) in fair value of cash flow hedge	(2,896)	3,010	(1,592)	(126)
Less: reclassification adjustment for amounts recognized in net income	(1,185)	(1,209)	(3,318)	(2,927)
Total other comprehensive income (loss)	(3,680)	1,085	(5,348)	(2,429)
Comprehensive income	30,297	26,601	90,180	72,523
Less: comprehensive income attributable to noncontrolling interest	(377)	(266)	(1,062)	(872)
Comprehensive income attributable to common stockholders	$ 29,920	$ 26,335	$ 89,118	$ 71,651