DEPOSITS AND CUSTOMER REPURCHASE AGREEMENTS (Deposit Liabilities) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012
Banking and Thrift [Abstract]
Non-interest-bearing accounts	$ 962,156	$ 981,240	$ 771,812
Interest-bearing checking	400,598	410,316	368,810
Regular savings accounts	759,866	727,957	673,704
Money market accounts	415,061	408,998	414,516
Total transaction and saving accounts	2,537,681	2,528,511	2,228,842
Certificates, within 1 year	705,933	759,626	918,696
Certificates, after 1 year, but within 3 years	220,615	209,790	210,161
Certificates, after 3 years	56,355	59,877	68,471
Total certificate accounts	982,903	1,029,293	1,197,328
Total deposits	3,520,584	3,557,804	3,426,170
Public fund transaction accounts	73,273	79,955	68,590
Public fund interest-bearing certificates	53,552	60,518	69,856
Total public deposits	126,825	140,473	138,446
Total brokered deposits	$ 15,709	$ 15,702	$ 30,978
Non-interest-bearing accounts, percent of total	27.30%	27.60%	22.50%
Interest-bearing checking, percent of total	11.40%	11.50%	10.80%
Regular savings accounts, percent of total	21.60%	20.50%	19.70%
Money market accounts, percent of total	11.80%	11.50%	12.10%
Total transaction and saving accounts, percent of total	72.10%	71.10%	65.10%
Certificates, within 1 year, percent of total	20.00%	21.30%	26.80%
Certificates, after 1 year, but within 3 years, percent of total	6.30%	5.90%	6.10%
Certificates, after 3 years, percent of total	1.60%	1.70%	2.00%
Total certificate accounts, percent of total	27.90%	28.90%	34.90%
Total deposits, percent of total	100.00%	100.00%	100.00%
Public fund transaction accounts, percent of total	2.10%	2.20%	2.00%
Public fund interest-bearing certificates, percent of total	1.50%	1.70%	2.00%
Total public deposits, percent of total	3.60%	3.90%	4.00%
Total brokered deposits, percent of total	0.40%	0.40%	0.90%