Junior Subordinated Debt - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) Trust Location	Dec. 31, 2018 USD ($)
Class of Stock [Line Items]
Number of subsidiary business trusts | Trust	5
Preferred stock, no par value: 1,000,000 shares authorized, zero issued and outstanding at December 31, 2018 and 2017 | $	$ 0	$ 0
Number of locations organized | Location	2
Wholly Owned Subsidiaries
Class of Stock [Line Items]
Preferred stock, no par value: 1,000,000 shares authorized, zero issued and outstanding at December 31, 2018 and 2017 | $	$ 62,900
North Valley Bancorp
Class of Stock [Line Items]
Number of subsidiary business trusts | Trust	3
Number of locations acquired | Location	3