Pending Acquisition of Bank of Rio Vista (Details) - Bank of Rio Vista [Member] $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018 USD ($) shares	Mar. 31, 2018 USD ($) shares	Sep. 30, 2018 USD ($) shares
Business Acquisition [Line Items]
Total ownership of shares (in shares) | shares		1,586
Percentage of ownership of common shares outstanding		39.65%
Total price paid for common shares		$ 12,000
Increase in recorded investment		$ 124
Forecast [Member]
Business Acquisition [Line Items]
Total ownership of shares (in shares) | shares	2,414		2,414
Percentage of ownership of common shares outstanding	60.35%		60.35%
Total price paid for common shares	$ 28,700		$ 40,700
Multiple of minimum book value to be delivered at close			1.42