Segment Information and Concentration of Business Risk, Revenue from Significant Partners (Details) - Partner	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Revenue [Member] | Customer Concentration [Member] | Partner A [Member]
Significant Partners [Abstract]
Concentration percentage	66.00%	72.00%	50.00%	48.00%
Revenue [Member] | Customer Concentration [Member] | Partner B [Member]
Significant Partners [Abstract]
Concentration percentage	16.00%	5.00%	14.00%	5.00%
Revenue [Member] | Customer Concentration [Member] | Partner C [Member]
Significant Partners [Abstract]
Concentration percentage	3.00%	4.00%	28.00%	4.00%
Revenue [Member] | Customer Concentration [Member] | Partner D [Member]
Significant Partners [Abstract]
Concentration percentage	5.00%	11.00%	2.00%	6.00%
Revenue [Member] | Customer Concentration [Member] | Partner E [Member]
Significant Partners [Abstract]
Concentration percentage	1.00%	0.00%	1.00%	29.00%
Contracts Receivables [Member] | Credit Concentration [Member] | Significant Partners [Member]
Significant Partners [Abstract]
Concentration percentage			92.00%		84.00%
Number of significant partners			4		2