Sales Concentration and Concentration of Credit Risk (Tables)

9 Months Ended

Sep. 30, 2015

Risks and Uncertainties [Abstract]

Sales concentration

		2014						2015
Customer		Sales % Three Months Ended September 30,			Sales % Nine Months Ended September 30,			Sales % Three Months Ended September 30,		Sales % Nine Months Ended September 30,			Accounts Receivable Balance as of September 30, 2015
	A		46	%		40	%		—		—		$	—
	B		25	%		18	%		—		—		$	—
	C		19	%		—			—		—		$	—
	D		—			17	%		—		—		$	—
	E		—			—			—		70	%	$	—
	F		—			—			—		22	%	$	—