Benefit Plans (Details 2) (USD $)	12 Months Ended			0 Months Ended	1 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Feb. 25, 2004	May 30, 2012	Dec. 31, 2016	May 31, 2014	Apr. 30, 2014	May 31, 2012
Additional disclosure
Compensation expense (in dollars)	$ 514,000	$ 943,000	$ 177,000
Stock option
Shares
Options outstanding at the beginning of the year (in shares)	813,670	672,334
Granted (in shares)	244,000	202,000
Exercised (in shares)	(132,586)	(57,164)
Forfeited and expired (in shares)		(3,500)
Options outstanding at the end of the year (in shares)	925,084	813,670	672,334
Options exercisable at the end of the year (in shares)	483,110	470,687
Weighted average exercise price per share
Options outstanding at the beginning of the year (in dollars per share)	$ 8.86	$ 8.34
Granted (in dollars per share)	$ 15.69	$ 10.64
Exercised (in dollars per share)	$ 10.65	$ 9.16
Forfeited and expired (in dollars per share)		$ 5.91
Options outstanding at the end of the year (in dollars per share)	$ 10.41	$ 8.86	$ 8.34
Weighted average remaining contractual life
Weighted average remaining contractual life of options outstanding at end of year	6 years 8 months 12 days	6 years
Additional disclosure
Aggregate intrinsic value (in dollars)	9,600,000	5,600,000	1,500,000
Aggregate intrinsic value of vested options	5,800,000	3,400,000	695,000
Aggregate intrinsic value of exercised options	536,000	277,000
Aggregate intrinsic value of forfeited and expired options		24,000
Compensation expense (in dollars)	514,000	943,000	177,000
Unrecognized compensation expense (in dollars)	$ 515,000					$ 292,000
Fair value assumptions:
Expected volatility (as a percent)			23.14%
Expected term	6 years	10 years	10 years
Risk free rate (as a percent)			1.57%
Weighted-average grant date fair value (in dollars per share)			$ 7.87
Stock option | Minimum
Fair value assumptions:
Expected volatility (as a percent)	16.20%	22.20%
Risk free rate (as a percent)	1.81%	1.78%
Weighted-average grant date fair value (in dollars per share)	$ 3.28	$ 3.93
Stock option | Maximum
Fair value assumptions:
Expected volatility (as a percent)	18.50%	25.82%
Risk free rate (as a percent)	2.10%	2.67%
Weighted-average grant date fair value (in dollars per share)	$ 3.67	$ 5.87
2004 Long-Term Incentive Plan
Share based plans
Shares authorized	525,500
Term of plan				10 years
Vesting percentage per year				33.30%
Shares
Granted (in shares)	0
Options outstanding at the end of the year (in shares)	325,355
2012 Plan
Share based plans
Shares authorized							1,420,000	800,000	620,000
Term of plan					10 years
Vesting percentage per year					33.30%
Shares
Granted (in shares)	816,105
Options outstanding at the end of the year (in shares)	599,729