Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Total	Preferred Stock	Common Stock	Additional Paid in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Beginning balance at Dec. 31, 2012	$ 269,475	$ 0	$ 18,507	$ 212,090	$ 38,314	$ 1,064	$ (500)
Beginning balance, preferred stock (shares) at Dec. 31, 2012		0
Beginning balance, common stock (shares) at Dec. 31, 2012			18,459,502
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	32,694				32,694
Other comprehensive income (loss)	(9,182)					(9,182)
Share-based compensation expense	3,368			3,368
Issuance of stock, net of offering costs	97,507		$ 6,179	91,328
Issuance of stock, net of offering costs (shares)			6,179,104
Exercise of warrants	264		$ 47	217
Exercise 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 (shares)			(484,641)
Ending balance at Dec. 31, 2013	386,623	$ 0	$ 24,756	307,231	71,008	(8,118)	(8,254)
Ending balance, common stock (shares) at Dec. 31, 2013			24,224,151
Ending balance, preferred stock (shares) at Dec. 31, 2013		0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	43,214				43,214
Other comprehensive income (loss)	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 of warrants	6		$ 1	5
Exercise 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	$ 0	$ 27,278	355,822	68,421	(122)	(8,254)
Ending balance, common stock (shares) at Dec. 31, 2014	26,745,529		26,745,529
Ending balance, preferred stock (shares) at Dec. 31, 2014	0	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 58,583				58,583
Other comprehensive income (loss)	(7,862)					(7,862)
Share-based compensation expense	4,862			4,862
Issuance of stock, net of offering costs	55,569	$ 55,569
Issuance of stock, net of offering costs (shares)		2,300,000
Preferred stock dividends	(2,493)				(2,493)
Exercise of warrants	98		$ 8	90
Exercise of warrants (shares)			7,611
Issuance of common stock under share-based-compensation arrangements	2,000		$ 146	1,833			21
Issuance of common stock under share-based-compensation arrangements (shares)			148,661
Ending balance at Dec. 31, 2015	$ 553,902	$ 55,569	$ 27,432	$ 362,607	$ 124,511	$ (7,984)	$ (8,233)
Ending balance, common stock (shares) at Dec. 31, 2015	26,901,801		26,901,801
Ending balance, preferred stock (shares) at Dec. 31, 2015	2,300,000	2,300,000