FAIR VALUE - Impairment of Valuation Adjustments were Recorded for Assets Recognized at Fair Value (Parenthetical) (Detail) - Fair Value Inputs Level 3 [Member] - Fair Value Measurements Nonrecurring [Member]	Dec. 31, 2017	Dec. 31, 2016
Measurement Input, Constant Prepayment Rate [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Servicing Asset, Measurement Input	0.063	0.0612
Measurement Input, Discount Rate [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Servicing Asset, Measurement Input	0.1123	0.1119