Fair Value Measurements - Impaired Loans Remeasured and Reported at Fair Value of Underlying Collateral (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying value of impaired loans before allocations	$ 89,562	$ 77,478
Specific valuation allowance allocations	(7,785)	$ (4,378)
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying value of impaired loans before allocations	0		$ 130
Specific valuation allowance allocations	0		(71)
Loans receivable, fair value disclosure	0		59
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying value of impaired loans before allocations	11,023		959
Specific valuation allowance allocations	(3,750)
Impaired Financing Receivable Related Allowance Reversal			150
Loans receivable, fair value disclosure	$ 7,273		$ 1,109