NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2013 RetailBranch		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2013 Segment RetailBranch	Dec. 31, 2012	Dec. 31, 2011
Nature of Operations [Abstract]
Trust Preferred securities payable	$ 70,680								$ 70,680								$ 70,680	$ 70,680
Number of retail branches	25																25
Loans [Abstract]
Minimum performance period before a non-accrual loan is classified current																	6 months
Accounting for Goodwill and Other Intangible Assets [Abstract]
Goodwill	55,638								55,638								55,638	55,638
Earnings Per Share Reconciliation [Abstract]
Net income	10,308		10,631		12,039		10,570		6,735		11,795		11,531		10,247		43,548	40,308	47,309
Less: Dividends paid on earnings allocated to participating securities																	(180)	(184)	(180)
Income attributable to common stock																	43,368	40,124	47,129
Weighted average common shares outstanding, including participating securities (in shares)																	35,507,765	34,623,287	34,041,171
Less: weighted average participating securities																	(320,566)	(327,326)	(318,387)
Weighted average common shares outstanding (in shares)																	35,187,199	34,295,961	33,722,784
Basic earnings per common share (in dollars per share)	$ 0.29	[1]	$ 0.30	[1]	$ 0.34	[1]	$ 0.30	[1]	$ 0.19	[1]	$ 0.34	[1]	$ 0.34	[1]	$ 0.30	[1]	$ 1.24	$ 1.18	$ 1.40
Income attributable to common stock																	43,368	40,124	47,129
Weighted average common shares outstanding																	35,187,199	34,295,961	33,722,784
Weighted average common equivalent shares outstanding (in shares)																	119,073	68,492	78,643
Weighted average common equivalent shares outstanding (in shares)																	35,306,272	34,364,453	33,801,427
Diluted earnings per common share (in dollars per share)	$ 0.29	[1]	$ 0.30	[1]	$ 0.34	[1]	$ 0.30	[1]	$ 0.19	[1]	$ 0.34	[1]	$ 0.34	[1]	$ 0.30	[1]	$ 1.23	$ 1.17	$ 1.40
Disclosure About Segments of an Enterprise and Related Information [Abstract]
Number of reportable segments																	1
Number of operating segments																	1
Customer measurement threshold to revenue, Minimum (in hundredths)																	10.00%
Accumulated Other Comprehensive Income (Loss) [Abstract]
Total accumulated other comprehensive loss, net of tax							9,640								9,709		9,640	9,709
Total accumulated other comprehensive loss, net of tax	$ 4,759								$ 9,640								$ 4,759	$ 9,640	$ 9,709
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average shares excluded from earnings per share calculation (in shares)																	901,037	1,279,708	2,116,374
Building [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Depreciation (in hundredths)																	2.22%
Building [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Depreciation (in hundredths)																	2.50%
Furniture, Fixtures, Equipment [Member]
Property, Plant and Equipment [Line Items]
Depreciation (in hundredths)																	10.00%

[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.