Share-Based Compensation Plan - Stock options outstanding activity (Details) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Shares [Roll Forward]
Outstanding at beginning of year (in shares)	30,012
Granted (in shares)	0
Exercised (in shares)	(4,638)
Forfeited (in shares)	0
Outstanding at end of period (in shares)	25,374
Options exercisable at year end (in shares)	25,374
Weighted Average Exercise Price [Roll Forward]
Outstanding at beginning of year (in dollars per share)	$ 14.00
Granted (in dollars per share)	0.00
Exercised (in dollars per share)	14.00
Forfeited (in dollars per share)	0.00
Outstanding at end of period (in dollars per share)	14.00
Options exercisable at year end (in dollars per share)	$ 14.00
Aggregate intrinsic value, options outstanding	$ 335		$ 0
Aggregate intrinsic value, options exercisable	$ 335