Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Net income	$ 33,093	$ 29,016	$ 23,069	$ 26,288	$ 26,157	$ 22,545	$ 19,064	$ 20,945	$ 111,466	$ 88,711	$ 69,447
Other comprehensive income (loss), net of tax:
Unrealized (losses) gains on hedging derivatives, net of taxes of $186, $382, and $104 for the years ended December 31, 2014, 2013 and 2012, respectively									(300)	565	137
Unrealized (losses) gains on available for sale securities, net of taxes of $60 and $11 for the years ended December 31, 2014 and 2013, respectively									(93)	16
Comprehensive income									$ 111,073	$ 89,292	$ 69,584