Summary of Significant Accounting Policies - Computation of Basic and Diluted net loss per share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accounting Policies [Abstract]
Income (Loss) from Continuing Operations Attributable to Parent											$ (15,611)
Net loss from continuing operations									$ (4,103)	$ (13,233)	(15,611)
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent									0	0	(8,715)
Net Income (Loss) Attributable to Parent	$ (1,237)	$ (1,228)	$ (763)	$ (875)	$ (5,599)	$ (1,047)	$ (5,163)	$ (1,424)	$ (4,103)	$ (13,233)	$ (24,326)
Weighted Average Number of Shares Outstanding, Basic	4,432,000	4,431,000	4,420,000	4,417,000	4,416,000	4,413,000	4,406,000	4,395,000	4,425,000	4,409,000	4,350,000
Weighted Average Number Diluted Shares Outstanding Adjustment									0	0	0
Weighted Average Number of Shares Outstanding, Diluted	4,432,000	4,431,000	4,420,000	4,417,000	4,416,000	4,413,000	4,406,000	4,395,000	4,425,000	4,409,000	4,350,000
Basic and diluted net loss per share from continuing operations attributable to Echelon Corporation Stockholders	$ (0.28)	$ (0.28)	$ (0.17)	$ (0.20)	$ (1.27)	$ (0.24)	$ (1.17)	$ (0.32)	$ (0.93)	$ (3.00)	$ (3.59)
Basic and diluted net loss per share from discontinued operations attributable to Echelon Corporation Stockholders									0.00	0.00	(2.00)
Basic and diluted net loss per share attributable to Echelon Corporation Stockholders									$ (0.93)	$ (3.00)	$ (5.59)
Stock Awards Excluded from Computation of Earnings Per Share Amount									837,035	367,363	406,134