Consolidated Statements of Changes in Shareholders' Equity (USD $) In Thousands, except Share data	Total	Common Stock	Additional Paid in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Beginning balance at Dec. 31, 2011	$ 147,748	$ 11,395	$ 122,602	$ 14,496	$ (245)	$ (500)
Beginning balance, shares at Dec. 31, 2011		11,347,683
Net income	23,818			23,818
Other comprehensive income	1,309				1,309
Share-based compensation expense	2,014		2,014
Issuance of common stock, net of costs	94,586	7,112	87,474
Issuance of common stock, net of costs (shares)		7,111,819
Ending balance at Dec. 31, 2012	269,475	18,507	212,090	38,314	1,064	(500)
Ending balance, shares at Dec. 31, 2012		18,459,502
Net income	32,694			32,694
Other comprehensive income	(9,182)				(9,182)
Share-based compensation expense	3,368		3,368
Issuance of common stock, net of costs	97,507	6,179	91,328
Issuance of common stock, net of costs (shares)		6,179,104
Exercise and redemption of warrants	264	47	217
Exercise and redemption of warrants (shares)		46,773
Issuance of common stock under share-based-compensation arrangements	251	23	228
Issuance of common stock under share-based-compensation arrangements, shares		23,413
Repurchase of shares	(7,754)					(7,754)
Repurchase of shares (in shares)		(484,641)
Ending balance at Dec. 31, 2013	386,623	24,756	307,231	71,008	(8,118)	(8,254)
Ending balance, shares at Dec. 31, 2013	24,224,151	24,224,151
Net income	43,214			43,214
Other comprehensive income	7,996				7,996
Stock dividend	(8)	2,429	43,364	(45,801)
Stock dividend, shares		2,429,375
Share-based compensation expense	4,209		4,209
Exercise and redemption of warrants	6	1	5
Exercise and redemption of warrants (shares)		546
Issuance of common stock under share-based-compensation arrangements	1,105	92	1,013
Issuance of common stock under share-based-compensation arrangements, shares		91,457
Ending balance at Dec. 31, 2014	$ 443,145	$ 27,278	$ 355,822	$ 68,421	$ (122)	$ (8,254)
Ending balance, shares at Dec. 31, 2014	26,745,529	26,745,529