Consolidated Statements of Changes in Equity (Unaudited) (USD $) In Thousands, unless otherwise specified	Total	Preferred Stock [Member]	Common Stock [Member]	Capital Surplus [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]
Balance at beginning of period at Dec. 31, 2013	$ 439,460	$ 81,698	$ 18,399	$ 91,632	$ 265,067	$ (17,336)	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	19,323				6,890	12,433
Cash dividends declared:
Preferred	(204)				(204)
Common	(1,845)				(1,845)
Purchase of noncontrolling interest	0
Purchase of shares of common stock	(606)						(606)
Issuance of shares of common stock	109		56	(531)			584
Commitments to issue common stock	1,098			1,098
Balance at end of period at Mar. 31, 2014	457,335	81,698	18,455	92,199	269,908	(4,903)	(22)
Balance at beginning of period at Dec. 31, 2014	496,317	81,698	18,511	95,816	298,764	1,528	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	19,436				15,709	3,727
Cash dividends declared:
Preferred	(204)				(204)
Common	(2,057)				(2,057)
Purchase of shares of common stock	(1,780)						(1,780)
Issuance of shares of common stock	54,496		2,075	50,687			1,734
Commitments to issue common stock	1,139			1,139
Balance at end of period at Mar. 31, 2015	$ 567,347	$ 81,698	$ 20,586	$ 147,642	$ 312,212	$ 5,255	$ (46)