Goodwill and Other Intangible Assets - Other Intangible Assets (Details) - USD ($) $ in Thousands			1 Months Ended
	Aug. 20, 2015	Nov. 01, 2014	Jun. 30, 2007	Mar. 31, 2016	Dec. 31, 2015
Diablo Valley Bank
Other Intangible Assets
Accumulated amortization				$ 4,810	$ 4,703
Diablo Valley Bank | Core deposit
Other Intangible Assets
Intangible assets acquired			$ 5,049
Useful life, amortization period			10 years
Diablo Valley Bank | Customer relationship
Other Intangible Assets
Intangible assets acquired			$ 276
Useful life, amortization period			7 years
Focus Business Bank | Core deposit
Other Intangible Assets
Intangible assets acquired	$ 6,285
Accumulated amortization				496	288
Useful life, amortization period	10 years
BVF/CSNK
Other Intangible Assets
Accumulated amortization				$ 437	$ 360
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 agreements
Other Intangible Assets
Intangible assets acquired		$ 250
Useful life, amortization period		3 years