Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net income		$ 131,252	$ 102,088	$ 100,569
Other comprehensive (loss) income:
Net unrealized (loss) gain on available-for-sale securities	[1]	(2,316)	(17,955)	32,635
Reclassification of unrealized gain on available-for-sale securities to net income		(21,167)	(29,426)	(10,552)
Net unrealized gain (loss) on interest rate agreements		3,271	(1,409)	(30,325)
Reclassification of unrealized loss on interest rate agreements to net income		72	95	164
Total other comprehensive (loss) income		(20,140)	(48,695)	(8,078)
Total Comprehensive Income		111,112	53,393	92,491
Other comprehensive income (loss). before reclassification adjustments, tax benefit (provision)		$ 1,000	$ (400)	$ (2,000)

[1] Amounts are presented net of tax benefit (provision) of $1 million, $(0.4) million, and $(2) million for the years ended December 31, 2016, 2015, and 2014, respectively.