Fair Value Measurements, Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Percentage of selling costs		10.00%
Investment Securities Available-for-Sale		$ 491,289	$ 495,396	$ 495,814
Level 1 to Level 2 transfers		0
Level 2 to Level 1 transfers		0
Transfer into Level 3		0
Transfer out of Level 3		0
Gains (losses) for assets categorized as Level 3 assets		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	3,039	3,095
US Treasury Notes [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale		164,674	164,514	143,409
US Govt SBA [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale		14,412	15,447	27,537
Mortgage Backed Securities [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale	[1]	304,020	307,045	318,763
Other [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale		5,156	5,351	3,010
Significant Unobservable Inputs (Level 3) [Member] | SBA Loans [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale		3,000
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
Recurring [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale		491,289	495,396	495,814
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	3,039	3,095
Recurring [Member] | US Treasury Notes [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale		164,674	164,514	143,409
Recurring [Member] | US Govt SBA [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale		14,412	15,447	27,537
Recurring [Member] | Mortgage Backed Securities [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale		304,020	307,045	318,763
Recurring [Member] | Other [Member]
Assets Measured at Fair Value on Recurring Basis by Fair Value Hierarchy [Abstract]
Investment Securities Available-for-Sale		5,156	5,351	3,010
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		164,877	164,716	143,609
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	0	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		164,674	164,514	143,409
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		203	202	200
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		321,769	325,841	349,705
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	3,039	3,095
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		14,412	15,447	27,537
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		304,020	307,045	318,763
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		4,643	4,839	2,500
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	0	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		$ 4,643	$ 4,839	$ 2,500

[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.