Basis of Presentation (Details)	1 Months Ended			3 Months Ended		12 Months Ended
	Oct. 31, 2019	May 31, 2018	Apr. 30, 2018	Mar. 31, 2020 USD ($) segment	Mar. 31, 2019 USD ($)	Dec. 31, 2019 USD ($)	Jan. 01, 2020 USD ($)	Dec. 31, 2018 USD ($)
Number of customers accounting for more than 10 percent of revenue for HBC or the Company				0
Number of operating segments | segment				2
Operating lease, right-of-use asset				$ 38,098,000
Operating lease liability				38,098,000
Allowance for credit losses on debt securities				55,000			$ 58,000
Loans, net of deferred fees				2,554,169,000		$ 2,534,163,000
Allowance for credit losses on loans				44,703,000		23,285,000	31,855,000
Allowance for credit losses on off-balance sheet credit exposures							679,000
Provision (credit) for credit losses on loans(1)				13,270,000	$ (1,061,000)
Impact of adopting Topic 326						(6,062,000)
Retained earnings				84,803,000		96,741,000
Debt Securities, Held-to-maturity, Credit Loss reduction				(3,000)
Off-Balance Sheet, Credit Loss, Liability, Credit Loss reduction				$ (305,000)
Tri Valley Bank and United American Bank | Core deposit
Finite-Lived Intangible Asset, Useful Life				10 years
Tri Valley Bank | Core deposit
Finite-Lived Intangible Asset, Useful Life			10 years
Tri Valley Bank | Below market-value lease
Finite-Lived Intangible Asset, Useful Life			11 years	11 years
United American Bank | Core deposit
Finite-Lived Intangible Asset, Useful Life		10 years
United American Bank | Below market-value lease
Finite-Lived Intangible Asset, Useful Life		3 years		3 years
Presidio bank
Finite-Lived Intangible Asset, Useful Life	60 months
Presidio bank | Core deposit
Finite-Lived Intangible Asset, Useful Life	10 years
Presidio bank | Below or Above market-value lease
Finite-Lived Intangible Asset, Useful Life	60 months			5 years
ASU 2016-03 - Topic 326
Allowance for credit losses on loans						8,570,000
ASU 2016-03 - Topic 326 | Restatement Adjustment
Allowance for credit losses on debt securities						58,000
Allowance for credit losses on loans						8,570,000
Allowance for credit losses on off-balance sheet credit exposures						(207,000)
Retained earnings						(6,062,000)
Amount of related income tax effect of a cumulative effect on retained earnings						2,357,000
ASU 2016-03 - Topic 326 | Previously Reported
Allowance for credit losses on loans						23,285,000
Allowance for credit losses on off-balance sheet credit exposures						886,000
Commercial
Loans, net of deferred fees				$ 682,280,000			6,790,000
Allowance for credit losses on loans				12,801,000	15,557,000	10,453,000	6,790,000	$ 17,061,000
Provision (credit) for credit losses on loans(1)				6,472,000	(1,993,000)
Commercial | ASU 2016-03 - Topic 326
Allowance for credit losses on loans						(3,663,000)
Commercial | ASU 2016-03 - Topic 326 | Restatement Adjustment
Loans, net of deferred fees						(3,663,000)
Commercial | ASU 2016-03 - Topic 326 | Previously Reported
Loans, net of deferred fees						10,453,000
CRE - owner occupied
Loans, net of deferred fees				543,164,000			6,994,000
Allowance for credit losses on loans				7,737,000		3,825,000	6,994,000
Provision (credit) for credit losses on loans(1)				743,000
CRE - owner occupied | ASU 2016-03 - Topic 326
Allowance for credit losses on loans						3,169,000
CRE - owner occupied | ASU 2016-03 - Topic 326 | Restatement Adjustment
Loans, net of deferred fees						3,169,000
CRE - owner occupied | ASU 2016-03 - Topic 326 | Previously Reported
Loans, net of deferred fees						3,825,000
CRE - non-owner occupied
Loans, net of deferred fees				755,008,000		767,821,000	11,672,000
Allowance for credit losses on loans				15,645,000		3,760,000	11,672,000
Provision (credit) for credit losses on loans(1)				3,973,000
CRE - non-owner occupied | ASU 2016-03 - Topic 326
Allowance for credit losses on loans						7,912,000
CRE - non-owner occupied | ASU 2016-03 - Topic 326 | Restatement Adjustment
Loans, net of deferred fees						7,912,000
CRE - non-owner occupied | ASU 2016-03 - Topic 326 | Previously Reported
Loans, net of deferred fees						3,760,000
Land and construction
Loans, net of deferred fees				153,358,000			1,458,000
Allowance for credit losses on loans				2,603,000	27,318,000	2,621,000	1,458,000	$ 27,848,000
Provision (credit) for credit losses on loans(1)				1,126,000	$ (1,061,000)
Land and construction | ASU 2016-03 - Topic 326
Allowance for credit losses on loans						(1,163,000)
Land and construction | ASU 2016-03 - Topic 326 | Restatement Adjustment
Loans, net of deferred fees						(1,163,000)
Land and construction | ASU 2016-03 - Topic 326 | Previously Reported
Loans, net of deferred fees						2,621,000
Home equity
Loans, net of deferred fees				117,768,000			1,321,000
Allowance for credit losses on loans				1,746,000		2,244,000	1,321,000
Provision (credit) for credit losses on loans(1)				402,000
Home equity | ASU 2016-03 - Topic 326
Allowance for credit losses on loans						(923,000)
Home equity | ASU 2016-03 - Topic 326 | Restatement Adjustment
Loans, net of deferred fees						(923,000)
Home equity | ASU 2016-03 - Topic 326 | Previously Reported
Loans, net of deferred fees						2,244,000
Multi-family
Loans, net of deferred fees				172,875,000			1,253,000
Allowance for credit losses on loans				1,622,000		57,000	1,253,000
Provision (credit) for credit losses on loans(1)				369,000
Multi-family | ASU 2016-03 - Topic 326
Allowance for credit losses on loans						1,196,000
Multi-family | ASU 2016-03 - Topic 326 | Restatement Adjustment
Loans, net of deferred fees						1,196,000
Multi-family | ASU 2016-03 - Topic 326 | Previously Reported
Loans, net of deferred fees						57,000
Residential mortgages
Loans, net of deferred fees				96,271,000			678,000
Allowance for credit losses on loans				708,000		243,000	678,000
Provision (credit) for credit losses on loans(1)				30,000
Residential mortgages | ASU 2016-03 - Topic 326
Allowance for credit losses on loans						435,000
Residential mortgages | ASU 2016-03 - Topic 326 | Restatement Adjustment
Loans, net of deferred fees						435,000
Residential mortgages | ASU 2016-03 - Topic 326 | Previously Reported
Loans, net of deferred fees						243,000
Consumer and other
Loans, net of deferred fees							1,689,000
Allowance for credit losses on loans				1,841,000		82,000	$ 1,689,000
Provision (credit) for credit losses on loans(1)				155,000
Consumer and other | ASU 2016-03 - Topic 326
Allowance for credit losses on loans						1,607,000
Consumer and other | ASU 2016-03 - Topic 326 | Restatement Adjustment
Loans, net of deferred fees						1,607,000
Consumer and other | ASU 2016-03 - Topic 326 | Previously Reported
Loans, net of deferred fees						$ 82,000
Consumer
Loans, net of deferred fees				$ 33,445,000