Fair Value Measurements - Fair Values and Related Carrying Amounts of Financial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Carrying Value
Financial assets:
Cash and cash equivalents	$ 131,532	$ 113,921
Interest-bearing deposits with financial institutions	3,917	4,665
Federal Reserve Bank of San Francisco and Federal Home Loan Bank stock	8,170	8,170
Loans, net	872,198	849,733
Accrued interest receivable	2,377	2,266
Financial liabilities:
Noninterest bearing deposits	294,153	249,676
Interest-bearing deposits	642,516	644,164
Borrowings	10,000	10,000
Junior subordinated debentures	17,527	17,527
Accrued interest payable	180	255
Total
Financial assets:
Cash and cash equivalents	131,532	113,921
Interest-bearing deposits with financial institutions	3,917	4,665
Federal Reserve Bank of San Francisco and Federal Home Loan Bank stock	8,170	8,170
Loans, net	874,006	846,690
Accrued interest receivable	2,377	2,266
Financial liabilities:
Noninterest bearing deposits	294,153	249,676
Interest-bearing deposits	642,667	643,935
Borrowings	10,024	9,999
Junior subordinated debentures	17,527	17,527
Accrued interest payable	180	255
Level 1
Financial assets:
Cash and cash equivalents	131,532	113,921
Interest-bearing deposits with financial institutions	3,917	4,665
Federal Reserve Bank of San Francisco and Federal Home Loan Bank stock	8,170	8,170
Loans, net	0	0
Accrued interest receivable	2,377	2,266
Financial liabilities:
Noninterest bearing deposits	294,153	249,676
Interest-bearing deposits	0	0
Borrowings	0	0
Junior subordinated debentures	0	0
Accrued interest payable	180	255
Level 2
Financial assets:
Cash and cash equivalents	0	0
Interest-bearing deposits with financial institutions	0	0
Federal Reserve Bank of San Francisco and Federal Home Loan Bank stock	0	0
Loans, net	0	0
Accrued interest receivable	0	0
Financial liabilities:
Noninterest bearing deposits	0	0
Interest-bearing deposits	642,667	643,935
Borrowings	10,024	9,999
Junior subordinated debentures	17,527	17,527
Accrued interest payable	0	0
Level 3
Financial assets:
Cash and cash equivalents	0	0
Interest-bearing deposits with financial institutions	0	0
Federal Reserve Bank of San Francisco and Federal Home Loan Bank stock	0	0
Loans, net	874,006	846,690
Accrued interest receivable	0	0
Financial liabilities:
Noninterest bearing deposits	0	0
Interest-bearing deposits	0	0
Borrowings	0	0
Junior subordinated debentures	0	0
Accrued interest payable	$ 0	$ 0