Loans - Narrative (Details)		3 Months Ended	12 Months Ended
	Apr. 01, 2014 USD ($) purchased_loan	Mar. 31, 2016 USD ($) financing_commitment Contract	Dec. 31, 2015 USD ($) Contract
Loans [Abstract]
Net nonaccrual loans		$ 1,635,000	$ 2,125,000
Nonperforming loans minimum threshold for individual impairment evaluation		50,000
Recorded investment in loans considered to be impaired		42,138,000	34,640,000
Business Acquisition [Line Items]
Loans classified as troubled debt restructuring		$ 13,300,000	$ 13,700,000
Modifications during the period (in contract) | Contract		0
Number of commitments on TDR (in financial_commitment) | financing_commitment		0
Write down on TDR		$ 0
TDR with specific allowance (in contract) | Contract		0	0
TDR that subsequently defaulted (in contract) | Contract		0	0
Alaska Pacific Bank
Business Acquisition [Line Items]
Purchased impaired loans (in purchased_loans) | purchased_loan	18
Accretable difference on purchased loans		$ 0
Fair value of purchased credit impaired loans	$ 3,900,000	$ 1,400,000