Loans and Credit Quality - Narrative (Details)		12 Months Ended
	Apr. 01, 2014 USD ($) purchased_loan	Dec. 31, 2017 USD ($) financing_commitment contract	Dec. 31, 2016 USD ($) contract	Dec. 31, 2015 USD ($) contract
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans secured by real estate		71.00%
Loans unsecured		3.00%
Loans secured for general commercial uses		26.00%
Net nonaccrual loans		$ 21,159,000	$ 12,480,000
Interest income earned on nonaccrual loans		1,400,000	676,000	$ 276,000
Interest income earned on nonaccrual loans with no balance		120,000	181,000	617,000
Greater than 90 days still accruing		252,000	456,000
Recorded investment in loans considered to be impaired		31,967,000	38,656,000
Impaired loan, average recorded investment		36,895,000	42,599,000	26,000,000
Impaired loan, interest income on accrual method		983,000	2,354,000	$ 1,100,000
Loans classified as troubled debt restructuring		$ 23,847,000	16,200,000
Commitment to Lend | financing_commitment		0
Write down on TDR		$ 731,000	$ 0
TDR with specific impairment | contract		2	4
TDR that subsequently defaulted, recorded investment | contract		0	0	0
Loans pledged as collateral		$ 0	$ 0
Unfunded loan commitments		15,000	15,000
Alaska Pacific Bank
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased impaired loans | purchased_loan	18
Accretable difference on purchased loans	$ 0
Fair value of purchased credit impaired loans	$ 3,900,000	$ 923,000	$ 1,100,000
Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recovery time for market		18 months
Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recovery time for market		24 months