Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 17,822us-gaap_NetIncomeLoss	$ 15,244us-gaap_NetIncomeLoss
Other comprehensive income:
Change in unrealized net gain on available-for-sale securities	493	1,841
Change in value of interest rate cap	(6)	42
Comprehensive Income	$ 18,309us-gaap_ComprehensiveIncomeNetOfTax	$ 17,127us-gaap_ComprehensiveIncomeNetOfTax

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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