DEPOSITS AND CUSTOMER REPURCHASE AGREEMENTS (Deposit Liabilities) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011
Banking and Thrift [Abstract]
Non-interest-bearing accounts	$ 918,962	$ 777,563	$ 763,008
Interest-bearing checking	379,650	362,542	362,090
Regular savings accounts	689,322	669,596	670,210
Money market accounts	411,262	415,456	429,083
Total transaction and saving accounts	2,399,196	2,225,157	2,224,391
Certificates, within 1 year	818,283	972,315	1,045,171
Certificates, after 1 year, but within 3 years	205,030	214,091	204,040
Certificates, after 3 years	63,863	64,091	63,832
Total certificate accounts	1,087,176	1,250,497	1,313,043
Total deposits	3,486,372	3,475,654	3,537,434
Public fund transaction accounts	72,407	72,064	67,753
Public fund interest-bearing certificates	61,628	67,112	69,321
Total public deposits	134,035	139,176	137,074
Total brokered deposits	$ 21,403	$ 49,194	$ 59,576
Non-interest-bearing accounts, percent of total	26.30%	22.40%	21.60%
Interest-bearing checking, percent of total	10.90%	10.40%	10.20%
Regular savings accounts, percent of total	19.80%	19.30%	18.90%
Money market accounts, percent of total	11.80%	11.90%	12.10%
Total transaction and saving accounts, percent of total	68.80%	64.00%	62.80%
Certificates, within 1 year, percent of total	23.50%	28.00%	29.60%
Certificates, after 1 year, but within 3 years, percent of total	5.90%	6.20%	5.80%
Certificates, after 3 years, percent of total	1.80%	1.80%	1.80%
Total certificate accounts, percent of total	31.20%	36.00%	37.20%
Total deposits, percent of total	100.00%	100.00%	100.00%
Public fund transaction accounts, percent of total	2.10%	2.10%	1.90%
Public fund interest-bearing certificates, percent of total	1.70%	1.90%	2.00%
Total public deposits, percent of total	3.80%	4.00%	3.90%
Total brokered deposits, percent of total	0.60%	1.40%	1.70%