Loans and Leases - Outstanding Principal Balance and Carrying Amount of Loans and Included in Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Outstanding principal and carrying value of acquired loans recorded at fair value
Outstanding principal balance	$ 769,414	$ 1,016,785
Carrying amount	535,596	727,491
Commercial, Financial, Leasing, etc. [Member]
Outstanding principal and carrying value of acquired loans recorded at fair value
Carrying amount	21,114	27,073
Commercial Real Estate [Member]
Outstanding principal and carrying value of acquired loans recorded at fair value
Carrying amount	94,890	135,047
Residential Real Estate [Member]
Outstanding principal and carrying value of acquired loans recorded at fair value
Carrying amount	341,807	473,511
Consumer [Member]
Outstanding principal and carrying value of acquired loans recorded at fair value
Carrying amount	$ 77,785	$ 91,860