Earnings (loss) per share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Numerator
Net income (loss) - basic and diluted	$ 13,513	$ 646	$ (1,037)
Preferred stock dividend and accretion	(737)	(674)	(1,436)
Preferred stock principal forgiveness	0	4,404	0
Preferred stock dividend forgiveness	0	2,215	0
Net income (loss) available to common shareholders	$ 12,776	$ 6,591	$ (2,473)
Denominator
Weighted average shares outstanding - basic (in shares)	1,421	1,166	334
Dilutive effect of common stock options and restricted stock awards (in shares)	0	35	0
Weighted average shares outstanding - diluted (in shares)	1,421	1,201	334
Earnings (loss) per share - basic (in dollars per share)	$ 8.99	$ 5.65	$ (7.39)
Earnings (loss) per share - diluted (in dollars per share)	$ 8.99	$ 5.49	$ (7.39)