Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 20,299	$ 21,036	$ 62,626	$ 64,822
Other comprehensive (loss) income:
Change in unrealized net gain or loss on available-for-sale securities	(1,653)	(2,419)	(8,494)	96
Change in value of interest rate cap	(11)	37	(67)	80
Comprehensive income	$ 18,635	$ 18,654	$ 54,065	$ 64,998

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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