FAIR VALUE - Impairment of Valuation Adjustments were Recorded for Assets Recognized at Fair Value (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2015		Dec. 31, 2014	Dec. 31, 2013
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Mortgage servicing rights	$ 22,026		$ 22,973		$ 22,838	$ 21,987
Loans Receivable [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets Fair Value Adjustment	(23,793)	[1]
Other Real Estate Owned [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets Fair Value Adjustment	(4,747)	[2]
Mortgage Servicing Rights [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets Fair Value Adjustment	(219)	[3]
Loans Held For Sale [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets Fair Value Adjustment	0	[4]
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			(13,725)	[5]
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			(2,711)	[2]
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			(38)	[6]
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	[4]
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	[1]	0	[5]
Other Real Estate Owned	0	[2]	0	[2]
Mortgage servicing rights	0	[3]	0	[6]
Loans held for sale	0	[4]	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	[1]	0	[5]
Other Real Estate Owned	0	[2]	0	[2]
Mortgage servicing rights	0	[3]	0	[6]
Loans held for sale	0	[4]	0	[4]
Fair Value Inputs Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Loans receivable	478,393	[1]
Other Real Estate Owned	138,622	[2]
Mortgage servicing rights	22,026	[3]
Loans held for sale	54,755	[4]
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			436,944	[5]
Other Real Estate Owned			122,628	[2]
Mortgage servicing rights			22,973	[6]
Loans held for sale			$ 54,588	[4]

[1]  Mainly impaired commercial and construction loans. The impairment was generally measured based on the fair value of the collateral. The fair values were 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-9.10%, Discount Rate-10.61%.

[4] The value of these loans was derived from external appraisals, adjusted for specific characteristics of the loans, and, for loans with signed sale agreements, the value was determined based on the sales price in such agreements.

[5] Mainly impaired commercial and construction loans. The impairment was generally measured based on the fair value of the collateral. The fair values were 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] 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-10.25%, Discount Rate-10.62%.