Summary of Significant Accounting Policies - Goodwill and Other Intangible Assets (Details)			1 Months Ended
	Aug. 20, 2015	Nov. 01, 2014	Jun. 30, 2007
Focus Business Bank
Goodwill and Other Intangible Assets
Useful life, amortization period	10 years
Core deposit | Diablo Valley Bank
Goodwill and Other Intangible Assets
Useful life, amortization period			10 years
Core deposit | Focus Business Bank
Goodwill and Other Intangible Assets
Useful life, amortization period	10 years
Below market-value lease | BVF/CSNK
Goodwill and Other Intangible Assets
Useful life, amortization period		3 years
Customer relationship | Diablo Valley Bank
Goodwill and Other Intangible Assets
Useful life, amortization period			7 years
Customer relationship and brokered relationship | BVF/CSNK
Goodwill and Other Intangible Assets
Useful life, amortization period		10 years
Non-compete agreements | BVF/CSNK
Goodwill and Other Intangible Assets
Useful life, amortization period		3 years