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Investment Securities - Securities Sold, Pledged as Collateral and Transfers (Details) - USD ($) $ in Thousands		12 Months Ended
	Feb. 24, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Available-for-sale:
Sales proceeds		$ 68,673	$ 2,099	$ 2,436
Gross realized gains		458	7	4
Gross realized losses		(64)	(1)	(28)
Held-to-maturity:
Sales proceeds		1,265	1,015	2,146
Gross realized gains		32	73	104
Gross realized losses		0	0	0
Securities transferred from available-for-sale to held-to-maturity		0	0	$ 14,297
Subsequent event
Held-to-maturity:
Securities transferred from available-for-sale to held-to-maturity	$ 129,000
Unrealized pre-tax loss from transfer of available-for-sale securities to held-to-maturity	$ 3,000
State of California
Available-for-sale:
Available-for-sale securities pledged as collateral		109,100	87,900
Public Deposits
Available-for-sale:
Available-for-sale securities pledged as collateral		108,300	87,100
Trust Deposits
Available-for-sale:
Available-for-sale securities pledged as collateral		822	840
Internal checking account
Available-for-sale:
Available-for-sale securities pledged as collateral		$ 2,100	$ 1,100

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This item represents the gross profit realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 9
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27357-111563

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 9
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27357-111563

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Sum of the carrying amounts as of the date of the latest financial statement presented of securities which are owned but transferred to another party to serve as collateral to partially or fully secure a debt obligation, repurchase agreement or other current or potential obligation, and for which the transferee is not permitted to sell or re-pledge them to an unrelated party.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 50
-Paragraph 1A
-Subparagraph (b)(1)(i)
-URI http://asc.fasb.org/extlink&oid=64858031&loc=SL6224234-111729

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The cash inflow associated with the sale of debt and equity securities classified as available-for-sale securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Investing Activities
-URI http://asc.fasb.org/extlink&oid=6516133

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The cash inflow associated with the sale of securities that had been designated as held-to-maturity. Excludes proceeds from maturities, prepayments and calls by the issuer.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-URI http://asc.fasb.org/extlink&oid=6516133

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