UNAUDITED QUARTERLY FINANCIAL INFORMATION (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	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, 2012	Dec. 31, 2011	Dec. 31, 2010
UNAUDITED QUARTERLY FINANCIAL INFORMATION [Abstract]
Net interest income	$ 8,551	[1]	$ 33,398		$ 34,498		$ 33,394		$ 34,127		$ 34,172		$ 36,160		$ 35,043		$ 109,842	$ 139,502	$ 135,381
Provision for loan losses	63		126		2,275		1,457		1,541		2,217		1,662		1,426		3,921	6,846	11,209
Net interest income after provision for loan losses	8,488		33,272		32,223		31,937		32,586		31,955		34,498		33,617		105,921	132,656	124,172
Non-interest (loss) income	16,498	[1]	2,574		2,988		1,790		2,136		2,149		1,734		1,910		23,849	7,929	8,055
Non-interest expense	14,717		15,771		15,676		16,408		14,781		14,964		15,083		16,860		62,572	61,688	61,977
Income before income taxes	10,269		20,075		19,535		17,319		19,941		19,140		21,149		18,667		67,198	78,897	70,250
Income tax expense	3,534		8,280		8,004		7,072		7,214		7,976		8,811		7,587		26,890	31,588	28,861
Net income	$ 6,735		$ 11,795		$ 11,531		$ 10,247		$ 12,727		$ 11,164		$ 12,338		$ 11,080		$ 40,308	$ 47,309	$ 41,389
Earnings per share:
Basic (in dollars per share)	$ 0.19	[2]	$ 0.34	[2]	$ 0.34	[2]	$ 0.30	[2]	$ 0.38	[3]	$ 0.33	[3]	$ 0.37	[3]	$ 0.33	[3]	$ 1.18	$ 1.4	$ 1.24
Diluted (in dollars per share)	$ 0.19	[2]	$ 0.34	[2]	$ 0.34	[2]	$ 0.30	[2]	$ 0.38	[3]	$ 0.33	[3]	$ 0.36	[3]	$ 0.33	[3]	$ 1.17	$ 1.40	$ 1.24

[1] (1) During the three months ended December 31, 2012, a charge of $25,582 on the prepayment of REPOS was recognized as a reduction to net interest income, and a gain on the sale of premises and fixed assets of $13,726 was recognized as a component of non-interest income.

[2] (2) The quarterly EPS amounts, when added, may not coincide with the full fiscal year EPS reported on the Consolidated Statements of Operations due to differences in the computed weighted average shares outstanding as well as rounding differences.

[3] (1) The quarterly EPS amounts, when added, may not coincide with the full fiscal year EPS reported on the Consolidated Statements of Operations due to differences in the computed weighted average shares outstanding as well as rounding differences.