Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	0 Months Ended		3 Months Ended																12 Months Ended
	Jul. 16, 2014	Jul. 02, 2013	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
Earnings Per Share [Abstract]
Net income			$ 10,533		$ 12,440		$ 11,363		$ 9,822		$ 7,766		$ 10,522		$ 12,119		$ 7,140		$ 44,158		$ 37,547		$ 27,449
Basic weighted average shares																			54,809,319	[1]	55,119,150	[1]	55,237,755	[1]
Effect of dilutive stock options and restricted stock																			559,697	[1]	468,231	[1]	335,484	[1]
Diluted weighted average shares																			55,369,016	[1]	55,587,381	[1]	55,573,239	[1]
Basic (usd per share)			$ 0.19	[1]	$ 0.23	[1]	$ 0.21	[1]	$ 0.18	[1]	$ 0.14	[1]	$ 0.19	[1]	$ 0.22	[1]	$ 0.13	[1]	$ 0.81	[1]	$ 0.68	[1]	$ 0.50	[1]
Diluted (usd per share)			$ 0.19	[1]	$ 0.22	[1]	$ 0.20	[1]	$ 0.17	[1]	$ 0.14	[1]	$ 0.19	[1]	$ 0.22	[1]	$ 0.13	[1]	$ 0.80	[1]	$ 0.68	[1]	$ 0.49	[1]
Anti-dilutive shares (in shares)																			32,436	[1]	206,264	[1]	929,870	[1]
Stock split, conversion ratio	1.5	1.5

[1] Reflects three-for-two stock split effective July 16, 2014