Loans - Narrative (Details) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2016 USD ($) Contract	Jun. 30, 2015 Contract	Dec. 31, 2013 Contract	Dec. 31, 2012 Contract	Dec. 31, 2011 Contract	Dec. 31, 2010 Contract	Dec. 31, 2015 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Period of financing receivable, updated valuation on real estate secured loans, 90 days past due	90 days
Impaired financing receivable, valuation on real estate collateralized loans	30 days
Period for order of valuations (at least)	18 months
Number of troubled debt restructured loan paid off		1
Number of loans which has periodic payments	1
Number of forbearance agreements modified					1
Number of forbearance agreements negotiated			1	3		1
Number of forbearance agreements that have expired	2
Consumer mortgage loans | $	$ 791						$ 583
Residential mortgage and commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Threshold period past due to discontinue accrual interest on financing receivable	90 days
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Threshold period past due for write-off of financing receivable (no later than)	120 days
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, term	20 years
Financing receivable, loan to value ratio of appraised value of property	80.00%
Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, term	30 years
Financing receivable, loan to value ratio of appraised value of property	80.00%
Home equity lines of credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, term	20 years
Financing receivable, loan to value ratio of appraised value of property	90.00%