Commitments and Contingencies - Summary of Off-Balance Sheet Financial Instruments (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Financial instruments with contract amounts which represent potential credit risk:
Loan commitments	$ 2,104,096	$ 1,303,458
Commercial mortgage loan commitments
Financial instruments with contract amounts which represent potential credit risk:
Loan commitments	106,626	43,624
Commercial loan commitments
Financial instruments with contract amounts which represent potential credit risk:
Loan commitments	919,353	629,729
Commercial owner-occupied commitments
Financial instruments with contract amounts which represent potential credit risk:
Loan commitments	57,144	43,879
Commercial standby letters of credit
Financial instruments with contract amounts which represent potential credit risk:
Loan commitments	148,131	71,233
Residential mortgage loan commitments
Financial instruments with contract amounts which represent potential credit risk:
Loan commitments	5,317	6,297
Consumer loan commitments
Financial instruments with contract amounts which represent potential credit risk:
Loan commitments	506,544	330,929
Construction loan commitments
Financial instruments with contract amounts which represent potential credit risk:
Loan commitments	$ 360,981	$ 177,767