Concentration of Risk (Details) - customer	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Revenue | Customer concentration risk | One customer
Concentration of risk
Number of customers	3	2	2	1
Percentage of concentration risk		32.80%	12.30%	33.00%
Revenue | Customer concentration risk | Second customer
Concentration of risk
Number of customers	3	2	2
Percentage of concentration risk		16.10%	10.10%
Revenue | Customer concentration risk | Third customer
Concentration of risk
Number of customers	3
Consolidated accounts receivable | Customer concentration risk | One customer
Concentration of risk
Number of customers			2		3
Consolidated accounts receivable | Customer concentration risk | Second customer
Concentration of risk
Number of customers			2		3
Consolidated accounts receivable | Customer concentration risk | Third customer
Concentration of risk
Number of customers					3
Consolidated accounts receivable | Credit concentration risk | One customer
Concentration of risk
Percentage of concentration risk	16.00%		27.00%		22.90%
Consolidated accounts receivable | Credit concentration risk | Second customer
Concentration of risk
Percentage of concentration risk	12.00%				12.70%
Consolidated accounts receivable | Credit concentration risk | Third customer
Concentration of risk
Percentage of concentration risk	11.70%		16.00%		11.60%