Goodwill and Other Intangible Assets - Other Intangible Assets (Details) - USD ($) $ in Thousands			1 Months Ended
	Aug. 20, 2015	Nov. 01, 2014	Sep. 30, 2017	Dec. 31, 2016	Jun. 30, 2007
Diablo Valley Bank
Other Intangible Assets
Accumulated amortization				$ 4,854
Diablo Valley Bank | Core deposit
Other Intangible Assets
Intangible assets acquired					$ 5,049
Useful life, amortization period			10 years
Focus Business Bank | Core deposit
Other Intangible Assets
Intangible assets acquired	$ 6,285
Accumulated amortization			$ 1,776	1,120
Useful life, amortization period	10 years
BVF/CSNK
Other Intangible Assets
Accumulated amortization			$ 901	$ 669
BVF/CSNK | Below market-value lease
Other Intangible Assets
Intangible assets acquired		$ 109
Useful life, amortization period		3 years
BVF/CSNK | Customer relationship and brokered relationship
Other Intangible Assets
Intangible assets acquired		$ 1,900
Useful life, amortization period		10 years
BVF/CSNK | Non-compete agreement
Other Intangible Assets
Intangible assets acquired		$ 250
Useful life, amortization period		3 years