Joint Venture	3 Months Ended
Mar. 31, 2018
Less Than Wholly Owned Subsidiary [Abstract]
Joint Venture	Joint Venture: On March 23, 2012, the Company entered into an agreement with Holley Metering Limited (“Holley Metering”), a designer and manufacturer of energy meters in China, to create a joint venture, Zhejiang Echelon-Holley Technology Co., Ltd. (“Echelon-Holley”). The joint venture's intended focus was on the development and sales of smart energy products for China and rest-of-world markets. The Company had a 51.0% ownership interest in the joint venture and exercised controlling influence. Therefore, Echelon-Holley’s accounts have been included in the Company’s condensed consolidated financial statements up until the point of its liquidation (see below). Holley Metering’s interests in Echelon-Holley’s net assets were reported in the non-controlling interest in subsidiary on the condensed consolidated balance sheet as of December 31, 2017. Net loss attributable to the non-controlling interest in Echelon-Holley was $0 and $0 during the three months ended March 31, 2018 and 2017, respectively. As of March 23, 2018, Echelon and Holley Metering had contributed in cash a total of approximately $4.0 million in Share Capital, as defined in the joint venture agreement, to Echelon-Holley in proportion to their respective ownership interests. In connection with the decision to sell the Grid business announced in the third quarter of 2014, the Company undertook a process to sell the remaining net assets of the joint venture and recorded the net assets and liabilities of the joint venture at the lower of their carrying amount or fair value less cost to sell, and classified them as held for sale on the accompanying balance sheet at December 31, 2014. The major classes of assets and liabilities that were classified as held for sale were inventory, deferred revenues and the related deferred costs of sales, and accrued liabilities. During the quarter ended September 30, 2015, the Company concluded that it would no longer pursue a sale, but would instead work with Holley Metering to shut the joint venture down. The remaining net assets of the joint venture were immaterial as of September 30, 2015. In early April 2018, the Company was informed by the Chinese authorities that the liquidation of Echelon-Holley had been completed on March 23, 2018. This resulted in a gain on liquidation of approximately $424,000, which is reflected in the Interest and other income (expense), net line in the Company's Condensed Consolidated Statement of Operations for the quarter ended March 31, 2018. In conjunction with the liquidation, the Company is required to remit approximately $438,000 to Holley Metering, which represents Holley-Metering's share of the remaining cash balance on the liquidation date. This payable obligation is reflected in Accrued Liabilities on the Company's Condensed Consolidated Balance Sheet at March 31, 2018.

Joint Venture:

On March 23, 2012, the Company entered into an agreement with Holley Metering Limited (“Holley Metering”), a designer and manufacturer of energy meters in China, to create a joint venture, Zhejiang Echelon-Holley Technology Co., Ltd. (“Echelon-Holley”). The joint venture's intended focus was on the development and sales of smart energy products for China and rest-of-world markets. The Company had a 51.0% ownership interest in the joint venture and exercised controlling influence. Therefore, Echelon-Holley’s accounts have been included in the Company’s condensed consolidated financial statements up until the point of its liquidation (see below). Holley Metering’s interests in Echelon-Holley’s net assets were reported in the non-controlling interest in subsidiary on the condensed consolidated balance sheet as of December 31, 2017. Net loss attributable to the non-controlling interest in Echelon-Holley was $0 and $0 during the three months ended March 31, 2018 and 2017, respectively.

As of March 23, 2018, Echelon and Holley Metering had contributed in cash a total of approximately $4.0 million in Share Capital, as defined in the joint venture agreement, to Echelon-Holley in proportion to their respective ownership interests.

In connection with the decision to sell the Grid business announced in the third quarter of 2014, the Company undertook a process to sell the remaining net assets of the joint venture and recorded the net assets and liabilities of the joint venture at the lower of their carrying amount or fair value less cost to sell, and classified them as held for sale on the accompanying balance sheet at December 31, 2014. The major classes of assets and liabilities that were classified as held for sale were inventory, deferred revenues and the related deferred costs of sales, and accrued liabilities.

During the quarter ended September 30, 2015, the Company concluded that it would no longer pursue a sale, but would instead work with Holley Metering to shut the joint venture down. The remaining net assets of the joint venture were immaterial as of September 30, 2015.

In early April 2018, the Company was informed by the Chinese authorities that the liquidation of Echelon-Holley had been completed on March 23, 2018. This resulted in a gain on liquidation of approximately $424,000, which is reflected in the Interest and other income (expense), net line in the Company's Condensed Consolidated Statement of Operations for the quarter ended March 31, 2018. In conjunction with the liquidation, the Company is required to remit approximately $438,000 to Holley Metering, which represents Holley-Metering's share of the remaining cash balance on the liquidation date. This payable obligation is reflected in Accrued Liabilities on the Company's Condensed Consolidated Balance Sheet at March 31, 2018.