Derivative Financial Instruments - Summary of Fair Value of Derivative Financial Instruments (Detail) - USD ($)	Sep. 30, 2020	Dec. 31, 2019
Derivative [Line Items]
Total derivative assets	$ 154,318,000	$ 51,301,000
Total derivative liabilities	18,776,000	12,393,000
Fair values of counterparty interest rate swaps	0
Interest rate contracts net adjustment	109,200,000	31,600,000
Derivatives designated as hedging instruments
Derivative [Line Items]
Total derivative assets	18,758,000	7,157,000
Total derivative liabilities	2,367,000	1,046,000
Derivatives designated as hedging instruments | Interest rate contracts | Other assets
Derivative [Line Items]
Total derivative assets	18,758,000	7,157,000
Derivatives designated as hedging instruments | Interest rate contracts | Other liabilities
Derivative [Line Items]
Total derivative liabilities	2,367,000	1,046,000
Derivatives not designated as hedging instruments
Derivative [Line Items]
Total derivative assets	135,560,000	44,144,000
Total derivative liabilities	16,409,000	11,347,000
Derivatives not designated as hedging instruments | Interest rate contracts | Other assets
Derivative [Line Items]
Total derivative assets	124,712,000	42,224,000
Derivatives not designated as hedging instruments | Interest rate contracts | Other liabilities
Derivative [Line Items]
Total derivative liabilities	16,282,000	10,883,000
Derivatives not designated as hedging instruments | Mortgage contracts | Other assets
Derivative [Line Items]
Total derivative assets	10,592,000	1,702,000
Derivatives not designated as hedging instruments | Mortgage contracts | Other liabilities
Derivative [Line Items]
Total derivative liabilities	0	354,000
Derivatives not designated as hedging instruments | Foreign currency contracts | Other assets
Derivative [Line Items]
Total derivative assets	256,000	218,000
Derivatives not designated as hedging instruments | Foreign currency contracts | Other liabilities
Derivative [Line Items]
Total derivative liabilities	$ 127,000	$ 110,000