Components of Net Deferred Tax Asset (Liability) (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred Tax Assets:
Allowance for loan losses	$ 45,611	$ 46,239
Compensation and related benefit obligations	19,693	13,010
Acquisition accounting and fair value adjustments on securities (including OTTI)	6,728	0
Non-accrual interest	431	818
Restructuring and retirement of borrowed funds	0	1,105
Net operating loss carryforwards	0	2,967
Other	11,349	15,953
Gross deferred tax assets	83,812	80,092
Valuation allowance	0	0
Deferred tax asset after valuation allowance	83,812	80,092
Deferred Tax Liabilities:
Amortizable intangibles	(2,263)	(1,704)
Acquisition accounting and fair value adjustments on securities (including OTTI)	0	(17,090)
Undistributed earnings of subsidiaries	0	(19,003)
Mortgage servicing rights	(223)	(1,794)
Premises and equipment	(11,242)	(12,907)
Prepaid pension cost	(19,135)	(24,324)
Leases	(115,259)	(78,682)
Other	(14,800)	(9,385)
Gross deferred tax liabilities	(162,922)	(164,889)
Net deferred tax liability	$ (79,110)	$ (84,797)