Stock Option Plan - Option Plan (Details) - Option Plan - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Number of shares
Balance at beginning of year (in shares)	627,000	649,000	528,000
Granted (in shares)			165,000
Exercised (in shares)	(66,000)
Forfeited (in shares)	(99,000)	(22,000)	(44,000)
Balance at end of year (in shares)	462,000	627,000	649,000	528,000
Exercisable (in shares)	421,667
Weighted-Average Exercise Price
Balance at beginning of year (in dollars per share)	$ 0.0004	$ 0.0004	$ 0.0004
Granted (in dollars per share)			0.0005
Exercised (in dollars per share)	0.0005
Forfeited (in dollars per share)	0.0003	0.0001	0.0005
Balance at end of year (in dollars per share)	0.0003	$ 0.0004	$ 0.0004	$ 0.0004
Exercisable at end of year (in dollars per share)	$ 0.0004
Weighted- Average Remaining Contractual Term (in Years)
Weighted-Average Remaining Contractual Term (in years)	5 years 6 months 26 days	6 years 5 months 9 days	7 years 4 months 6 days	7 years 5 months 23 days
Exercisable	5 years 5 months 23 days
Number of unvested options scheduled to vest
Unvested options (in shares)	40,333
2016
Number of unvested options scheduled to vest
Unvested options (in shares)	40,333
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option life (in years)	10 years
Weighted- Average Remaining Contractual Term (in Years)
Aggregate intrinsic value of stock option awards outstanding	$ 4,925
Aggregate intrinsic value of stock option awards exercisable	$ 4,495