Stock Options (Details) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Apr. 05, 2012
Stock options under 2012 Plan
Stock option details
Shares available for future grants	199,250		800,000
Maximum exercisable period for options granted	10 years
Stock option activity
Options outstanding at the beginning of the period (in shares)	515,143
Plus: Options granted (in shares)	549,750
Less:
Options exercised (in shares)	8,399
Options forfeited (in shares)	500
Options outstanding at the end of the period (in shares)	1,055,994
Options fully vested and exercisable at the end of the period (in shares)	222,942
Stock options, weighted average exercise price
Options outstanding at the beginning, weighted average exercise price (in dollars per share)	$ 15.98
Plus: Options granted, weighted average exercise price (in dollars per share)	$ 21.42
Less:
Options exercised, weighted average exercise price (in dollars per share)	$ 14.23
Options forfeited, weighted average exercise price (in dollars per share)	$ 10.40
Options outstanding at the end, weighted average exercise price (in dollars per share)	$ 18.83
Options fully vested and exercisable at the end, weighted average exercise price (in dollars per share)	$ 18.43
Stock options, weighted average remaining contractual term
Options outstanding at the end, weighted average remaining contractual term	6 years
Options fully vested and exercisable at the end, weighted average remaining contractual term	2 years 5 months 1 day
Stock options, aggregate intrinsic value
Options outstanding at the end, aggregate intrinsic value	$ 6,711,000
Options fully vested and exercisable at the end, aggregate intrinsic value	1,593,000
Stock-based compensation expense	161,000	114,000
Stock-based compensation cost, unrecognized, related to non-vested options	$ 4,831,000
Stock-based compensation cost, unrecognized, related to non-vested options, weighted-average period of recognition	2 years 7 months 6 days
Incentive stock options granted to 10% shareholders
Stock option details
Maximum exercisable period for options granted	5 years