Employee Benefit Plan (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Employee 401(k) Plan
Minimum age for contribution of an additional amount of salary per year by participants	50 years
Matching contribution by employer per dollar of contribution by participant	0.25%
Maximum contribution by employer (as a percent)	4.00%
Contribution by employer	$ 29,000	$ 28,000
Minimum
Employee 401(k) Plan
Contribution by participating employee (as a percent)	1.00%
Maximum
Employee 401(k) Plan
Contribution by participating employee (as a percent)	25.00%