Discontinued Operations (Details) - USD ($) $ in Thousands		3 Months Ended		12 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Discontinued Operations [Abstract]
Disposal Group, Including Discontinued Operation, Description and Timing of Disposal				9/30/2014
Proceeds from divestiture of Grid business, net of transaction costs			$ 4,900	$ 0	$ 0	$ 2,144
Supply commitment term		39 months
Restructuring Costs in Discontinued Operations				1,400
Revenues						18,392
Cost of revenues						11,774
Operating expenses						15,614
Loss from discontinued operations before income taxes						(8,996)
Income taxes						0
Loss on sale of Grid business				0	0	(254)
Net loss from discontinued operations, net of income taxes	[1]			0	0	(9,250)
Net loss from discontinued operations attributable to non-controlling interest, net of income taxes				0	0	(535)
Net loss from discontinued operations attributable to Echelon Corporation Stockholders, net of income taxes				$ 0	$ 0	(8,715)
Revenues from related parties, discontinued operations						$ 112

[1] See Note 8 for summary of amounts included representing stock-based compensation expense.