Derivative Financial Instruments and Hedging Activities - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Treasury Forward Interest Rate Locks (T-Locks)
Derivative [Line Items]
Period hedged items affected earnings, years	10 years
Derivative instruments hedge description	to hedge the risk that the 10-year U.S. Treasury yield would rise
Unrealized gain (loss) on derivatives	$ 900,000
Treasury Forward Interest Rate Locks (T-Locks) | Subordinated notes
Derivative [Line Items]
Senior notes issuance	500,000,000
Derivatives Designated as Hedging Instruments | Interest rate swaps | Cash flow | Loans
Derivative [Line Items]
Notional amounts of derivatives	$ 210,000,000.0	$ 210,000,000.0
LIBOR basis points	one-month LIBOR
Derivatives Designated as Hedging Instruments | Interest rate swaps | Subordinated notes | Fair value
Derivative [Line Items]
Notional amounts of derivatives	$ 375,000,000
LIBOR basis points	three-month LIBOR
Subordinated notes	$ 400,000,000
Basis points	1.265%
Derivatives Designated as Hedging Instruments | Interest rate swaps | FHLB advances | Cash flow
Derivative [Line Items]
Notional amounts of derivatives	$ 550,000,000	$ 0