FAIR VALUE DISCLOSURES (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Assets, Fair Value Disclosure, Recurring	$ 2,155,948	$ 2,505,400
Liabilities, Fair Value Disclosure, Recurring	6,570	7,645
United States Government Sponsored Enterprises Debt Securities [Member]
Assets, Fair Value Disclosure, Recurring	308,272	341,817
Residential Mortgage Backed Securitiess Debt Securities [Member]
Assets, Fair Value Disclosure, Recurring	1,576,744	1,924,920
Commercial Mortgage Backed Securities [Member]
Assets, Fair Value Disclosure, Recurring	924	910
Us States and Political Subdivisions [Member]
Assets, Fair Value Disclosure, Recurring	4,957	5,410
Corporate Note Securities [Member]
Assets, Fair Value Disclosure, Recurring	189,606	183,813
Equity Method Investments [Member]
Assets, Fair Value Disclosure, Recurring	1,032	1,017
Mortgage Loans Held For Sale [Member]
Assets, Fair Value Disclosure, Recurring	58,241	31,111
Customer Interest Rate Swap Agreements [Member]
Assets, Fair Value Disclosure, Recurring	118	370
Liabilities, Fair Value Disclosure, Recurring	118	307
Interest Rate Lock Commitments [Member]
Assets, Fair Value Disclosure, Recurring	4,282	1,381
Forward Commitments To Sell Mortgage Backed Securities [Member]
Assets, Fair Value Disclosure, Recurring	(2,322)	(729)
Servicing Rights Fair Value Disclosure [Member]
Assets, Fair Value Disclosure, Recurring	14,094	15,380
Interest Rate Swap [Member]
Liabilities, Fair Value Disclosure, Recurring	163	807
Nonqualified Deferred Compensation Plan [Member]
Liabilities, Fair Value Disclosure, Recurring	6,289	6,531
Fair Value, Inputs, Level 1 [Member]
Assets, Fair Value Disclosure, Recurring	1,032	1,017
Liabilities, Fair Value Disclosure, Recurring	6,289	6,531
Fair Value, Inputs, Level 1 [Member] | United States Government Sponsored Enterprises Debt Securities [Member]
Assets, Fair Value Disclosure, Recurring	0	0
Fair Value, Inputs, Level 1 [Member] | Residential Mortgage Backed Securitiess Debt Securities [Member]
Assets, Fair Value Disclosure, Recurring	0	0
Fair Value, Inputs, Level 1 [Member] | Commercial Mortgage Backed Securities [Member]
Assets, Fair Value Disclosure, Recurring	0	0
Fair Value, Inputs, Level 1 [Member] | Us States and Political Subdivisions [Member]
Assets, Fair Value Disclosure, Recurring	0	0
Fair Value, Inputs, Level 1 [Member] | Corporate Note Securities [Member]
Assets, Fair Value Disclosure, Recurring	0	0
Fair Value, Inputs, Level 1 [Member] | Equity Method Investments [Member]
Assets, Fair Value Disclosure, Recurring	1,032	1,017
Fair Value, Inputs, Level 1 [Member] | Mortgage Loans Held For Sale [Member]
Assets, Fair Value Disclosure, Recurring	0	0
Fair Value, Inputs, Level 1 [Member] | Customer Interest Rate Swap Agreements [Member]
Assets, Fair Value Disclosure, Recurring	0	0
Liabilities, Fair Value Disclosure, Recurring	0	0
Fair Value, Inputs, Level 1 [Member] | Interest Rate Lock Commitments [Member]
Assets, Fair Value Disclosure, Recurring	0	0
Fair Value, Inputs, Level 1 [Member] | Forward Commitments To Sell Mortgage Backed Securities [Member]
Assets, Fair Value Disclosure, Recurring	0	0
Fair Value, Inputs, Level 1 [Member] | Servicing Rights Fair Value Disclosure [Member]
Assets, Fair Value Disclosure, Recurring	0	0
Fair Value, Inputs, Level 1 [Member] | Interest Rate Swap [Member]
Liabilities, Fair Value Disclosure, Recurring	0	0
Fair Value, Inputs, Level 1 [Member] | Nonqualified Deferred Compensation Plan [Member]
Liabilities, Fair Value Disclosure, Recurring	6,289	6,531
Fair Value, Inputs, Level 2 [Member]
Assets, Fair Value Disclosure, Recurring	2,140,822	2,489,003
Liabilities, Fair Value Disclosure, Recurring	281	1,114
Fair Value, Inputs, Level 2 [Member] | United States Government Sponsored Enterprises Debt Securities [Member]
Assets, Fair Value Disclosure, Recurring	308,272	341,817
Fair Value, Inputs, Level 2 [Member] | Residential Mortgage Backed Securitiess Debt Securities [Member]
Assets, Fair Value Disclosure, Recurring	1,576,744	1,924,920
Fair Value, Inputs, Level 2 [Member] | Commercial Mortgage Backed Securities [Member]
Assets, Fair Value Disclosure, Recurring	924	910
Fair Value, Inputs, Level 2 [Member] | Us States and Political Subdivisions [Member]
Assets, Fair Value Disclosure, Recurring	4,957	5,410
Fair Value, Inputs, Level 2 [Member] | Corporate Note Securities [Member]
Assets, Fair Value Disclosure, Recurring	189,606	183,813
Fair Value, Inputs, Level 2 [Member] | Equity Method Investments [Member]
Assets, Fair Value Disclosure, Recurring	0	0
Fair Value, Inputs, Level 2 [Member] | Mortgage Loans Held For Sale [Member]
Assets, Fair Value Disclosure, Recurring	58,241	31,111
Fair Value, Inputs, Level 2 [Member] | Customer Interest Rate Swap Agreements [Member]
Assets, Fair Value Disclosure, Recurring	118	370
Liabilities, Fair Value Disclosure, Recurring	118	307
Fair Value, Inputs, Level 2 [Member] | Interest Rate Lock Commitments [Member]
Assets, Fair Value Disclosure, Recurring	4,282	1,381
Fair Value, Inputs, Level 2 [Member] | Forward Commitments To Sell Mortgage Backed Securities [Member]
Assets, Fair Value Disclosure, Recurring	(2,322)	(729)
Fair Value, Inputs, Level 2 [Member] | Servicing Rights Fair Value Disclosure [Member]
Assets, Fair Value Disclosure, Recurring	0	0
Fair Value, Inputs, Level 2 [Member] | Interest Rate Swap [Member]
Liabilities, Fair Value Disclosure, Recurring	163	807
Fair Value, Inputs, Level 2 [Member] | Nonqualified Deferred Compensation Plan [Member]
Liabilities, Fair Value Disclosure, Recurring	0	0
Fair Value, Inputs, Level 3 [Member]
Assets, Fair Value Disclosure, Recurring	14,094	15,380
Liabilities, Fair Value Disclosure, Recurring	0	0
Fair Value, Inputs, Level 3 [Member] | United States Government Sponsored Enterprises Debt Securities [Member]
Assets, Fair Value Disclosure, Recurring	0	0
Fair Value, Inputs, Level 3 [Member] | Residential Mortgage Backed Securitiess Debt Securities [Member]
Assets, Fair Value Disclosure, Recurring	0	0
Fair Value, Inputs, Level 3 [Member] | Commercial Mortgage Backed Securities [Member]
Assets, Fair Value Disclosure, Recurring	0	0
Fair Value, Inputs, Level 3 [Member] | Us States and Political Subdivisions [Member]
Assets, Fair Value Disclosure, Recurring	0	0
Fair Value, Inputs, Level 3 [Member] | Corporate Note Securities [Member]
Assets, Fair Value Disclosure, Recurring	0	0
Fair Value, Inputs, Level 3 [Member] | Equity Method Investments [Member]
Assets, Fair Value Disclosure, Recurring	0	0
Fair Value, Inputs, Level 3 [Member] | Mortgage Loans Held For Sale [Member]
Assets, Fair Value Disclosure, Recurring	0	0
Fair Value, Inputs, Level 3 [Member] | Customer Interest Rate Swap Agreements [Member]
Assets, Fair Value Disclosure, Recurring	0	0
Liabilities, Fair Value Disclosure, Recurring	0	0
Fair Value, Inputs, Level 3 [Member] | Interest Rate Lock Commitments [Member]
Assets, Fair Value Disclosure, Recurring	0	0
Fair Value, Inputs, Level 3 [Member] | Forward Commitments To Sell Mortgage Backed Securities [Member]
Assets, Fair Value Disclosure, Recurring	0	0
Fair Value, Inputs, Level 3 [Member] | Servicing Rights Fair Value Disclosure [Member]
Assets, Fair Value Disclosure, Recurring	14,094	15,380
Fair Value, Inputs, Level 3 [Member] | Interest Rate Swap [Member]
Liabilities, Fair Value Disclosure, Recurring	0	0
Fair Value, Inputs, Level 3 [Member] | Nonqualified Deferred Compensation Plan [Member]
Liabilities, Fair Value Disclosure, Recurring	$ 0	$ 0