Fair Value Measurements (Impaired Loans Remeasured and Reported at Fair Value of Underlying Collateral) (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying value of impaired loans before allocations	$ 99,453	$ 70,221	$ 145,610
Specific valuation allowance allocations	(28,483)	(16,235)	(20,820)
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying value of impaired loans before allocations	2,354	12,517	0
Specific valuation allowance allocations	(383)	(2,599)	0
Fair value	1,971	9,918	0
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying value of impaired loans before allocations	65,176	22,688	75,435
Reversal of specific valuation allowance allocations		9,260
Specific valuation allowance allocations	(18,019)		(19,533)
Fair value	$ 47,157	$ 31,948	$ 55,902