Fair Value Measurements, Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale		$ 532,246	$ 491,289	$ 507,386
Level 1 to Level 2 transfers		0
Level 2 to Level 1 transfers		0
Transfer into Level 3		0	0
Transfer out of Level 3		0	0
Unrealized gain (losses) on investments			0
Government Agency & Government-Sponsored Entities [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale			3,027
US Treasury Notes [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale		15,399	164,674	54,995
US Govt SBA [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale		9,954	14,412	10,798
Mortgage Backed Securities [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale	[1]	501,376	304,020	441,078
Significant Unobservable Inputs (Level 3) [Member] | California Reclamation Districts [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale			1,400
Significant Unobservable Inputs (Level 3) [Member] | Pacific Coast Bankers' Bank and The Independent Bankers' Bank Stock [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale			200
Significant Unobservable Inputs (Level 3) [Member] | SBA Loan Fund Investment Measured at NAV [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale			3,000
Recurring [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale		532,246	491,289	507,386
Recurring [Member] | Government Agency & Government-Sponsored Entities [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale			3,027
Recurring [Member] | US Treasury Notes [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale		15,399	164,674	54,995
Recurring [Member] | US Govt SBA [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale		9,954	14,412	10,798
Recurring [Member] | Mortgage Backed Securities [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale		501,376	304,020	441,078
Recurring [Member] | Other [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale		5,517	5,156	515
Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale		20,606	164,877	55,200
Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Government Agency & Government-Sponsored Entities [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale			0
Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | US Treasury Notes [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale		15,399	164,674	54,995
Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | US Govt SBA [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale		0	0	0
Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Mortgage Backed Securities [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale		0	0	0
Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Other [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale		5,207	203	205
Recurring [Member] | Other Observable Inputs (Level 2) [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale		511,640	321,769	452,186
Recurring [Member] | Other Observable Inputs (Level 2) [Member] | Government Agency & Government-Sponsored Entities [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale			3,027
Recurring [Member] | Other Observable Inputs (Level 2) [Member] | US Treasury Notes [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale		0	0	0
Recurring [Member] | Other Observable Inputs (Level 2) [Member] | US Govt SBA [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale		9,954	14,412	10,798
Recurring [Member] | Other Observable Inputs (Level 2) [Member] | Mortgage Backed Securities [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale		501,376	304,020	441,078
Recurring [Member] | Other Observable Inputs (Level 2) [Member] | Other [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale		310	310	310
Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale		0	4,643	0
Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Government Agency & Government-Sponsored Entities [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale			0
Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | US Treasury Notes [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale		0	0	0
Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | US Govt SBA [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale		0	0	0
Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Mortgage Backed Securities [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale		0	0	0
Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Other [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale		$ 0	$ 4,643	$ 0

[1] All Mortgage Backed Securities consist of securities collateralized by residential real estate and were issued by an agency or government sponsored entity of the U.S. government.