Tax Incentive Agreement (Details) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)
Tax Incentive Agreement
Minimum number of years for which jobs must be maintained	5 years
Portion of job creation tax award recognized				0.20
Job creation tax award				$ 1.1
Revenue from job creation tax award recognized as other income		$ 0.2	$ 0.2	$ 0.2