Commitments and Contingencies - Financial Instruments with Off-Balance Sheet Risk (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Commitments and Contingencies
Commitments to extend credit, fixed rate	$ 20,319	$ 11,399
Commitments to extend credit, variable rate	$ 553,355	427,929
Expiration term of commitments (in years)	1 year
Reserves in the form of vault cash and balances at Federal Reserve Bank of San Francisco	$ 29,015
Unused lines of credit and commitments to make loans
Commitments and Contingencies
Commitments to extend credit, fixed rate	16,917	8,164
Commitments to extend credit, variable rate	539,897	415,146
Standby letters of credit
Commitments and Contingencies
Commitments to extend credit, fixed rate	3,402	3,235
Commitments to extend credit, variable rate	$ 13,458	$ 12,783