Income taxes (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Income taxes
Uncertain tax positions	$ 363	$ 459
Uncertain tax positions, reduction to deferred tax assets	84	106
Accrued interest, net of federal income tax benefits, and penalties	50	67
Unrecognized tax benefits that would affect the effective tax rate	229
Reconciliation of unrecognized tax benefits
Balance at the beginning of the period	392	392
Additions for current period tax positions	0	0
Effective settlement during the current period	(79)
Balance at the end of the period	$ 313	$ 392