Concentration of Risk (Details) - item	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Revenue | Customer concentration risk
Concentration of risk
Number of customers	2	2	1	2
Revenue | Customer concentration risk | One customer
Concentration of risk
Percentage of concentration risk	32.80%	11.00%	33.00%	18.80%
Revenue | Customer concentration risk | Second customer
Concentration of risk
Percentage of concentration risk	16.10%	10.50%		10.80%
Consolidated accounts receivable | Credit concentration risk
Concentration of risk
Number of customers			4		2
Consolidated accounts receivable | Credit concentration risk | One customer
Concentration of risk
Percentage of concentration risk			20.50%		21.70%
Consolidated accounts receivable | Credit concentration risk | Second customer
Concentration of risk
Percentage of concentration risk			12.30%		20.40%
Consolidated accounts receivable | Credit concentration risk | Third customer
Concentration of risk
Percentage of concentration risk			11.80%
Consolidated accounts receivable | Credit concentration risk | Fourth customer
Concentration of risk
Percentage of concentration risk			10.00%