Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Total	Series D Preferred Stock	Preferred Stock	Common Stock	Additional Paid in Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock
Beginning balance, preferred stock (shares) at Dec. 31, 2014			0
Beginning balance, common stock (shares) at Dec. 31, 2014				26,745,529
Beginning balance at Dec. 31, 2014	$ 443,145		$ 0	$ 27,278	$ 355,822	$ 68,421	$ (122)	$ (8,254)
Net income	13,952					13,952
Other comprehensive income (loss)	(925)						(925)
Share-based compensation expense	1,170				1,170
Issuance of common stock under share-based compensation arrangements (shares)				78,510
Issuance of common stock under share-based compensation arrangements	609			$ 78	531
Ending balance, preferred stock (shares) at Mar. 31, 2015			0
Ending balance, common stock (shares) at Mar. 31, 2015				26,824,039
Ending balance at Mar. 31, 2015	$ 457,951		$ 0	$ 27,356	357,523	82,373	(1,047)	(8,254)
Beginning balance, preferred stock (shares) at Dec. 31, 2015	2,300,000		2,300,000
Beginning balance, common stock (shares) at Dec. 31, 2015	26,901,801			26,901,801
Beginning balance at Dec. 31, 2015	$ 553,902		$ 55,569	$ 27,432	362,607	124,511	(7,984)	(8,233)
Net income	17,699					17,699
Other comprehensive income (loss)	2,651						2,651
Issuance of stock, net of offering costs (shares)			1,000,000	7,291
Issuance of stock, net of offering costs	159	$ 24,108	$ 24,108	$ 7	152
Preferred stock dividends	(1,286)					(1,286)
Share-based compensation expense	1,402				1,402
Exercise of warrants (shares)				12,377
Exercise of warrants	118			$ 12	106
Issuance of common stock under share-based compensation arrangements (shares)				115,536
Issuance of common stock under share-based compensation arrangements	$ 496			$ 116	380			0
Ending balance, preferred stock (shares) at Mar. 31, 2016	3,300,000		3,300,000
Ending balance, common stock (shares) at Mar. 31, 2016	27,037,005			27,037,005
Ending balance at Mar. 31, 2016	$ 599,249		$ 79,677	$ 27,567	$ 364,647	$ 140,924	$ (5,333)	$ (8,233)