Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Statement of Comprehensive Income [Abstract]
Net income	$ 25,516	$ 43,050	$ 74,952	$ 79,072
Other comprehensive income (loss):
Change in unrealized gains on securities	(716)	(627)	624	693
Increase (decrease) in fair value of cash flow hedge	3,010	159	(126)	1,531
Less: reclassification adjustment for amounts recognized in net income	(1,209)	(543)	(2,927)	(809)
Total other comprehensive income (loss)	1,085	(1,011)	(2,429)	1,415
Comprehensive income	26,601	42,039	72,523	80,487
Less: comprehensive income attributable to noncontrolling interest	(266)	(306)	(872)	(664)
Comprehensive income attributable to common stockholders	$ 26,335	$ 41,733	$ 71,651	$ 79,823