Loans and Credit Quality - Narrative (Details)		6 Months Ended	12 Months Ended
	Apr. 01, 2014 USD ($) purchased_loan	Jun. 30, 2017 USD ($) financing_commitment contract	Dec. 31, 2016 USD ($) contract
Receivables [Abstract]
Net nonaccrual loans		$ 21,050,000	$ 12,480,000
Nonperforming loans minimum threshold for individual impairment evaluation		50,000
Recorded investment in loans considered to be impaired		36,311,000	38,656,000
Business Acquisition [Line Items]
Loans classified as troubled debt restructuring		$ 25,405,000	$ 16,200,000
Number of commitments on TDR | financing_commitment		0
Charge offs on loans later classified as TDRs		$ 0
TDR with specific impairment | contract		0	4
TDR that subsequently defaulted | contract		0	0
Alaska Pacific Bancshares
Business Acquisition [Line Items]
Purchased impaired loans | purchased_loan	18
Accretable yield on purchased loans	$ 0
Fair value of purchased credit impaired loans	$ 3,900,000	$ 1,100,000