DERIVATIVES - Summary of Derivative Financial Instruments and Balances (Detail) (USD $) In Thousands	Sep. 30, 2011	Dec. 31, 2010
Derivatives, Fair Value [Line Items]
Notional Amount	$ 737,922	$ 578,959
Estimate Fair Value Gain	24,733	14,974
Estimate Fair Value Loss	(28,493)	(17,935)
Fair Value Hedges
Derivatives, Fair Value [Line Items]
Notional Amount	737,922	578,959
Fair Value Hedges | Pay fixed interest rate swaps with counterparty | Accrued interest and other liabilities
Derivatives, Fair Value [Line Items]
Notional Amount	17,688	21,301
Estimate Fair Value Gain	0	0
Estimate Fair Value Loss	(2,407)	(2,302)
Fair Value Hedges | Matched interest rate swaps | Accrued interest and other liabilities
Derivatives, Fair Value [Line Items]
Notional Amount	360,117	278,829
Estimate Fair Value Gain	0	131
Estimate Fair Value Loss	(26,086)	(15,502)
Fair Value Hedges | Matched interest rate swaps | Accrued interest and other assets
Derivatives, Fair Value [Line Items]
Notional Amount	360,117	278,829
Estimate Fair Value Gain	24,733	14,843
Estimate Fair Value Loss	0	(131)
Pay fixed interest rate swaps with counterparty
Derivatives, Fair Value [Line Items]
Notional Amount	$ 17,688