Derivatives and Hedging Activities - Summary of Fair Values of Derivative Instruments on Balance Sheets (Detail) - USD ($)	Jun. 30, 2021	Dec. 31, 2020
Derivatives, Fair Value [Line Items]
Asset Derivatives	$ 30,710,000	$ 47,120,000
Liability Derivatives	32,165,000	51,078,000
Interest Rate Swaps [Member] | Loan Swaps [Member]
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	723,672,000	649,857,000
Asset Derivatives	30,394,000	46,418,000
Liability Derivatives	32,165,000	49,917,000
Interest Rate Loan Commitments [Member] | Other Contract [Member]
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	52,346,000	112,119,000
Asset Derivatives	250,000	702,000
Forward TBA Contracts [Member] | Other Contract [Member]
Derivatives, Fair Value [Line Items]
Notional or Contractual Amount	83,000,000.0	183,500,000
Asset Derivatives	$ 66,000
Liability Derivatives		$ 1,161,000