Summary of Significant Accounting Policies - Additional Information (Detail) $ in Thousands	6 Months Ended
	Jun. 30, 2022 USD ($) county segment trust office
Significant Accounting Policies [Line Items]
Number of subsidiary business trusts (in trusts) | trust	5
Company's investments in the trusts | $	$ 1,751
Number of business segment (in segments) | segment	1
Loans contractual past due	90 days
North Valley Bancorp
Significant Accounting Policies [Line Items]
Number of loan production offices (in offices) | office	3
Minimum
Significant Accounting Policies [Line Items]
Loan term	5 years
Amortization period	15 years
Maximum
Significant Accounting Policies [Line Items]
Loan term	10 years
Amortization period	30 years
California
Significant Accounting Policies [Line Items]
Number of counties (in counties) | county	31