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	$ 18,172	$ 17,692	$ 53,335	$ 49,764
Other comprehensive income:
Change in unrealized net gain on available-for-sale securities	1,188	(1,563)	(3,527)	2,644
Change in value of interest rate cap	2	(30)	(8)	(183)
Comprehensive Income	$ 19,362	$ 16,099	$ 49,800	$ 52,225