REGULATORY MATTERS, Reconciliation of Stockholders' Equity to Regulatory Capital for the Bank (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Reconciliation of Stockholders' Equity to Regulatory Capital for the Bank [Line Items]
Stockholders' equity	$ 391,574	$ 361,034	$ 328,734
Non-allowable assets:
Accumulated other comprehensive loss	(9,640)	(9,709)
Total (Tier 2) risk-based capital	405,077	368,317
Minimum capital requirement	(383,042)	(359,838)
Tangible Capital [Member]
Reconciliation of Stockholders' Equity to Regulatory Capital for the Bank [Line Items]
Stockholders' equity	428,892	405,403
Non-allowable assets:
Mortgage Servicing Rights (MSR)	(111)	(162)
Accumulated other comprehensive loss	9,899	10,235
Goodwill	(55,638)	(55,638)
Tier I risk-based capital	383,042	359,838
General regulatory valuation allowance	0	0
Total (Tier 2) risk-based capital	383,042	359,838
Minimum capital requirement	153,493	118,561
Regulatory capital excess	229,549	241,277
Leverage Capital [Member]
Reconciliation of Stockholders' Equity to Regulatory Capital for the Bank [Line Items]
Stockholders' equity	428,892	405,403
Non-allowable assets:
Mortgage Servicing Rights (MSR)	(111)	(162)
Accumulated other comprehensive loss	9,899	10,235
Goodwill	(55,638)	(55,638)
Tier I risk-based capital	383,042	359,838
General regulatory valuation allowance	0	0
Total (Tier 2) risk-based capital	383,042	359,838
Minimum capital requirement	153,493	158,082
Regulatory capital excess	229,549	201,756
Total Risk-Based Capital [Member]
Reconciliation of Stockholders' Equity to Regulatory Capital for the Bank [Line Items]
Stockholders' equity	428,892	405,403
Non-allowable assets:
Mortgage Servicing Rights (MSR)	(111)	(162)
Accumulated other comprehensive loss	9,899	10,235
Goodwill	(55,638)	(55,638)
Tier I risk-based capital	383,042	359,838
General regulatory valuation allowance	22,035	8,479
Total (Tier 2) risk-based capital	405,077	368,317
Minimum capital requirement	228,232	240,760
Regulatory capital excess	$ 176,845	$ 127,557