Subordinated Debentures (Details) - USD ($)	3 Months Ended
	Sep. 30, 2016	Jun. 30, 2006	Mar. 31, 2004	Dec. 31, 2019
Subordinated Debt [Member]
Subordinated Borrowings [Line Items]
Proceeds from Issuance of Subordinated Long-term Debt	$ 7,217,000	$ 15,464,000	$ 15,464,000
Subordinated Borrowing, Due Date	Dec. 15, 2037	Sep. 23, 2036	Mar. 17, 2034
Subordinated Borrowing, Interest Rate	3.39%	3.33%	4.65%
Debt Instrument, Basis Spread on Variable Rate	1.50%	1.40%	2.75%
Statutory Trust [Member]
Subordinated Borrowings [Line Items]
Trust Preferred Securities Qualified As Tier One Capital				$ 34,945,000
Sierra Statutory Trust II [Member]
Subordinated Borrowings [Line Items]
Floating Rate Capital Trust Pass Through Securities Issued During Period		15,000	15,000
Floating rate capital trust pass through securities liquidation value per securities		$ 1,000	$ 1,000
Proceeds from Issuance of Mandatory Redeemable Capital Securities		$ 15,000,000	$ 15,000,000
Coast Bancorp Statutory Trust II [Member]
Subordinated Borrowings [Line Items]
Floating Rate Capital Trust Pass Through Securities Issued During Period	7,000
Floating rate capital trust pass through securities liquidation value per securities	$ 1,000
Proceeds from Issuance of Mandatory Redeemable Capital Securities	$ 7,000,000