FAIR VALUE - Impairment of Valuation Adjustments were Recorded for Assets Recognized at Fair Value (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2016		Mar. 31, 2015		Dec. 31, 2015	Dec. 31, 2014
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Mortgage servicing rights		$ 24,692		$ 22,973		$ 24,282	$ 22,838
Loans Receivable [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets Fair Value Adjustment	[1]			(13,725)
Other Real Estate Owned [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets Fair Value Adjustment	[2]			(2,711)
Mortgage Servicing Rights [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets Fair Value Adjustment	[3]			(38)
Loans Held For Sale [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets Fair Value Adjustment	[4]			0
Fair Value Measurements Nonrecurring [Member] | Loans Receivable [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets Fair Value Adjustment	[5]	675
Fair Value Measurements Nonrecurring [Member] | Other Real Estate Owned [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets Fair Value Adjustment	[6]	(2,910)
Fair Value Measurements Nonrecurring [Member] | Mortgage Servicing Rights [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets Fair Value Adjustment	[7]	27
Fair Value Measurements Nonrecurring [Member] | Loans Held For Sale [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets Fair Value Adjustment		0
Fair Value Inputs Level 1 [Member] | Fair Value Measurements Nonrecurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Loans receivable		0	[5]	0	[1]
Other Real Estate Owned		0	[6]	0	[2]
Mortgage servicing rights		0	[7]	0	[3]
Loans held for sale		0		0	[4]
Fair Value Inputs Level 2 [Member] | Fair Value Measurements Nonrecurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Loans receivable		0	[5]	0	[1]
Other Real Estate Owned		0	[6]	0	[2]
Mortgage servicing rights		0	[7]	0	[3]
Loans held for sale		0		0	[4]
Fair Value Inputs Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Loans receivable	[1]			436,944
Other Real Estate Owned	[2]			122,628
Mortgage servicing rights	[3]			22,973
Loans held for sale	[4]			$ 54,588
Fair Value Inputs Level 3 [Member] | Fair Value Measurements Nonrecurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Loans receivable	[5]	304,498
Other Real Estate Owned	[6]	142,888
Mortgage servicing rights	[7]	$ 24,692

[1] Consist mainly of impaired commercial and construction loans. The impairment was generally measured based on the fair value of the collateral. The fair value was derived from external appraisals that take into consideration prices in observed transactions involving similar assets in similar locations but adjusted for specific characteristics and assumptions of the collateral (e.g. absorption rates), which are not market observable.

[2] The fair value was derived from appraisals that take into consideration prices in observed transactions involving similar assets in similar locations but adjusted for specific characteristics and assumptions of the properties (e.g., absorption rates and net operating income of income producing properties), which are not market observable. Losses were related to market valuation adjustments after the transfer of the loan to the OREO portfolio.

[3] Fair value adjustments to the mortgage servicing rights were mainly due to assumptions associated with mortgage prepayments rates. The Corporation carries its mortgage servicing rights at the lower of cost or market, measured at fair value on a non-recurring basis. Assumptions for the value of mortgage servicing rights included: Prepayment Rate-10.25%, Discount Rate-10.62%.

[4] The value of these loans was derived from external appraisals, adjusted for specific characteristics of the loans.

[5] Consist mainly of impaired commercial and construction loans. The impairment was generally measured based on the fair value of the collateral. The fair value was derived from external appraisals that take into consideration prices in observed transactions involving similar assets in similar locations but adjusted for specific characteristics and assumptions of the collateral (e.g., absorption rates), which are not market observable.

[6] The fair value was derived from appraisals that take into consideration prices in observed transactions involving similar assets in similar locations but adjusted for specific characteristics and assumptions of the properties (e.g., absorption rates and net operating income of income producing properties), which are not market observable. Losses were related to market valuation adjustments after the transfer of the loan to the OREO portfolio.

[7] Fair value adjustments to mortgage servicing rights were mainly due to assumptions associated with mortgage prepayment rates. The Corporation carries its mortgage servicing rights at the lower of cost or market, measured at fair value on a non-recurring basis. Assumptions for the value of mortgage servicing rights included: Prepayment rate-10.06%, Discount Rate-10.66%.