Quarterly Results of Operations (Unaudited) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Quarterly Financial Information Disclosure [Abstract]
Interest Income	$ 45,707	$ 40,736	$ 40,653	$ 43,738	$ 42,964	$ 45,347	$ 44,169	$ 43,469	$ 170,834	$ 175,949	$ 181,245
Interest Expense	4,572	3,714	4,003	4,280	4,699	5,445	6,116	7,353	16,569	23,613	37,890
NET INTEREST INCOME	41,135	37,022	36,650	39,458	38,265	39,902	38,053	36,116	154,265	152,336	143,355
Provision for loan losses	1,016	1,533	1,997	2,102	4,505	4,609	4,545	4,875	6,648	18,534	22,630
NET INTEREST INCOME AFTER PROVISION FOR LOAN LOSSES	40,119	35,489	34,653	37,356	33,760	35,293	33,508	31,241	147,617	133,802	120,725
Noninterest Income	15,073	11,800	14,059	13,877	14,206	14,273	13,165	22,658	54,809	64,302	49,120
Noninterest Expense	40,558	34,219	33,742	34,700	34,503	34,404	34,180	34,028	143,219	137,115	135,938
INCOME BEFORE INCOME TAX	14,634	13,070	14,970	16,533	13,463	15,162	12,493	19,871	59,207	60,989	33,907
Income tax expense	3,187	2,667	4,155	4,668	3,153	3,926	3,288	5,500	14,677	15,867	8,655
NET INCOME	11,447	10,403	10,815	11,865	10,310	11,236	9,205	14,371	44,530	45,122	25,252
Preferred stock dividends	(241)	(430)	(852)	(857)	(1,135)	(1,134)	(1,135)	(1,135)	(2,380)	(4,539)	(3,981)
NET INCOME AVAILABLE TO COMMON STOCKHOLDERS	$ 11,206	$ 9,973	$ 9,963	$ 11,008	$ 9,175	$ 10,102	$ 8,070	$ 13,236	$ 42,150	$ 40,583	$ 9,013
Basic (usd per share)	$ 0.34	$ 0.35	$ 0.35	$ 0.38	$ 0.32	$ 0.35	$ 0.29	$ 0.46	$ 1.42	$ 1.42	$ 0.34
Diluted (usd per share)	$ 0.34	$ 0.35	$ 0.34	$ 0.38	$ 0.32	$ 0.35	$ 0.28	$ 0.46	$ 1.41	$ 1.41	$ 0.34
Weighted Average Number of Shares Outstanding, Basic	32,597,145	28,806,809	28,783,407	28,716,987	28,673,802	28,649,996	28,624,609	28,582,616	29,731,420	28,632,915	26,550,043
Weighted Average Number of Shares Outstanding, Diluted	32,912,605	29,081,472	29,023,513	28,971,238	28,930,392	28,888,076	28,815,019	28,754,713	30,008,380	28,846,684	26,693,848