SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED) (Details) (USD $) In Thousands, except Per 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, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Selected Quarterly Financial Information [Abstract]
Interest income	$ 44,595	$ 45,037	$ 45,571	$ 44,508	$ 45,525	$ 47,174	$ 47,265	$ 47,198	$ 48,451	$ 49,561	$ 49,888	$ 49,663	$ 179,712	$ 187,162	$ 197,563
Interest expense	2,988	3,144	3,323	3,540	3,991	4,476	4,975	6,072	6,865	7,833	8,687	9,607	12,996	19,514	32,992
Net interest income before provision for loan losses	41,607	41,893	42,248	40,968	41,534	42,698	42,290	41,126	41,586	41,728	41,201	40,056	166,716	167,648	164,571
Provision for loan losses	0	0	0	0	1,000	3,000	4,000	5,000	5,000	5,000	8,000	17,000	0	13,000	35,000
Net interest income	41,607	41,893	42,248	40,968	40,534	39,698	38,290	36,126	36,586	36,728	33,201	23,056	166,716	154,648	129,571
Other operating income	12,580	10,142	10,623	9,997	13,311	11,684	(9,064)	10,971	7,151	10,340	9,253	7,246	43,342	26,902	33,990
Other operating expenses	36,929	34,490	35,457	34,099	34,519	33,355	35,666	37,913	38,667	41,038	40,255	38,144	140,975	141,453	158,104
Income before provision for (benefit from) income taxes	17,258	17,545	17,414	16,866	19,326	18,027	(6,440)	9,184	5,070	6,030	2,199	(7,842)	69,083	40,097	5,457
Provision (benefit) for income taxes	5,704	5,880	5,661	5,284	4,638	2,407	(31,830)	0	0	0	0	0	22,528	(24,785)	0
NET INCOME	11,554	11,665	11,753	11,582	14,688	15,620	25,390	9,184	5,070	6,030	2,199	(7,842)	46,555	64,882	5,457
Preferred stock dividend	0	0	0	0	611	1,227	1,550	1,550	1,550	1,550	1,550	1,550	0	4,938	6,200
Preferred stock discount accretion	0	0	0	0	1,174	1,216	454	454	425	425	425	426	0	3,298	1,701
Gain on repurchase and retirement of preferred stock	0	0	0	0	(401)	(2,070)	0	0	0	0	0	0	0	(2,471)	0
NET INCOME (LOSS) AVAILABLE TO COMMON SHAREHOLDERS	$ 11,554	$ 11,665	$ 11,753	$ 11,582	$ 13,304	$ 15,247	$ 23,386	$ 7,180	$ 3,095	$ 4,055	$ 224	$ (9,818)	$ 46,555	$ 59,117	$ (2,444)
Basic earnings (loss) per share (in dollars per share)	$ 0.60	$ 0.60	$ 0.60	$ 0.60	$ 0.69	$ 0.81	$ 1.27	$ 0.40	$ 0.18	$ 0.24	$ 0.01	$ (0.61)	$ 2.40	$ 3.17	$ (0.15)
Diluted earnings (loss) per share (in dollars per share)	$ 0.60	$ 0.60	$ 0.60	$ 0.60	$ 0.69	$ 0.80	$ 1.27	$ 0.40	$ 0.18	$ 0.24	$ 0.01	$ (0.61)	$ 2.40	$ 3.16	$ (0.15)
Cumulative dividends declared per common share (in dollars per share)	$ 0.15	$ 0.15	$ 0.12	$ 0.12	$ 0.01	$ 0.01	$ 0.01	$ 0.01	$ 0.01	$ 0.01	$ 0.01	$ 0.07	$ 0.54	$ 0.04	$ 0.10