Commitments and Contingencies	9 Months Ended
Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Legal Contingencies From time to time, the Company is involved in legal and administrative proceedings and claims of various types. The Company records a liability in its consolidated financial statements for these matters when a loss is known or considered probable and the amount can be reasonably estimated. The Company reviews these estimates each accounting period as additional information is known and adjusts the loss provision when appropriate. If a matter is both probable to result in a liability and the amounts of loss can be reasonably estimated, the Company estimates and discloses the possible loss or range of loss to the extent necessary to make the consolidated financial statements not misleading. If the loss is not probable or cannot be reasonably estimated, a liability is not recorded in its consolidated financial statements. On September 13, 2011, the Company commenced a series of legal actions in China against Sinovel Wind Group Co. Ltd. (“Sinovel”). The Company’s Chinese subsidiary, Suzhou AMSC Superconductor Co. Ltd., filed a claim for arbitration with the Beijing Arbitration Commission in accordance with the terms of the Company’s supply contracts with Sinovel. The case is captioned (2011) Jing Zhong An Zi No. 963. The Company alleges that Sinovel committed various material breaches of its contracts with the Company and Sinovel has refused to pay past due amounts for prior shipments of core electrical components and spare parts. The Company is seeking compensation for past product shipments and retention (including interest) in the amount of approximately RMB 485 million (approximately $75 million) due to Sinovel’s breaches of its contracts. The Company is also seeking specific performance of its existing contracts as well as reimbursement of all costs and reasonable expenses with respect to the arbitration. The value of the undelivered components under the existing contracts, including the deliveries refused by Sinovel in March 2011, amounts to approximately RMB 4.6 billion (approximately $707 million). On October 8, 2011, Sinovel filed with the Beijing Arbitration Commission an application under the caption (2011) Jing Zhong An Zi No. 963, for a counterclaim against the Company for breach of the same contracts under which the Company filed its original arbitration claim. Sinovel claims, among other things, that the goods supplied by the Company do not conform to the standards specified in the contracts and claims damages in the amount of approximately RMB 1.2 billion (approximately $184 million) upon Sinovel’s requests for change of counterclaim. On February 27, 2012, Sinovel filed with the Beijing Arbitration Commission an application under the caption (2012) Jing Zhong An Zi No. 157, against the Company for breach of the same contracts under which the Company filed its original arbitration claim. Sinovel claims, among other things, that the goods supplied by the Company do not conform to the standards specified in the contracts and claims damages in the amount of approximately RMB 105 million (approximately $16 million). The Company believes that Sinovel’s claims are without merit and it intends to defend these actions vigorously. Since the proceedings in this matter are still in the early technical review phase, the Company cannot reasonably estimate possible losses or range of losses at this time. Other The Company enters into long-term construction contracts with customers that require the Company to obtain performance bonds. The Company is required to deposit an amount equivalent to some or all the face amount of the performance bonds into an escrow account until the termination of the bond. When the performance conditions are met, amounts deposited as collateral for the performance bonds are returned to the Company. In addition, the Company has various contractual arrangements in which minimum quantities of goods or services have been committed to be purchased on an annual basis. As of December 31, 2017, the Company had $0.2 million of restricted cash included in long-term assets. These amounts included in restricted cash primarily represent deposits to secure letters of credit for various supply contracts. These deposits are held in interest bearing accounts. During the nine months ended December 31, 2017, the Company received $1.0 million related to the achievement of certain milestones following the previous sale of the Company's minority interest in Blade Dynamics Limited. On September 25, 2017, the Company acquired ITC for a purchase price of approximately $3.8 million, consisting of $0.1 million in cash and the AMSC Shares. The Company paid certain selling stockholders the Make Whole Payment given that the value of the AMSC Shares sold was less than the agreed upon purchase price. The amount of this payment, which was made on January 5, 2018, was $0.7 million and settled the related contingent liability. See Note 4, “Acquisitions and Related Goodwill” for further discussion.

Commitments and Contingencies

Legal Contingencies

From time to time, the Company is involved in legal and administrative proceedings and claims of various types. The Company records a liability in its consolidated financial statements for these matters when a loss is known or considered probable and the amount can be reasonably estimated. The Company reviews these estimates each accounting period as additional information is known and adjusts the loss provision when appropriate. If a matter is both probable to result in a liability and the amounts of loss can be reasonably estimated, the Company estimates and discloses the possible loss or range of loss to the extent necessary to make the consolidated financial statements not misleading. If the loss is not probable or cannot be reasonably estimated, a liability is not recorded in its consolidated financial statements.

On September 13, 2011, the Company commenced a series of legal actions in China against Sinovel Wind Group Co. Ltd. (“Sinovel”). The Company’s Chinese subsidiary, Suzhou AMSC Superconductor Co. Ltd., filed a claim for arbitration with the Beijing Arbitration Commission in accordance with the terms of the Company’s supply contracts with Sinovel. The case is captioned (2011) Jing Zhong An Zi No. 963. The Company alleges that Sinovel committed various material breaches of its contracts with the Company and Sinovel has refused to pay past due amounts for prior shipments of core electrical components and spare parts. The Company is seeking compensation for past product shipments and retention (including interest) in the amount of approximately RMB 485 million (approximately $75 million) due to Sinovel’s breaches of its contracts. The Company is also seeking specific performance of its existing contracts as well as reimbursement of all costs and reasonable expenses with respect to the arbitration. The value of the undelivered components under the existing contracts, including the deliveries refused by Sinovel in March 2011, amounts to approximately RMB 4.6 billion (approximately $707 million).

On October 8, 2011, Sinovel filed with the Beijing Arbitration Commission an application under the caption (2011) Jing Zhong An Zi No. 963, for a counterclaim against the Company for breach of the same contracts under which the Company filed its original arbitration claim. Sinovel claims, among other things, that the goods supplied by the Company do not conform to the standards specified in the contracts and claims damages in the amount of approximately RMB 1.2 billion (approximately $184 million) upon Sinovel’s requests for change of counterclaim. On February 27, 2012, Sinovel filed with the Beijing Arbitration Commission an application under the caption (2012) Jing Zhong An Zi No. 157, against the Company for breach of the same contracts under which the Company filed its original arbitration claim. Sinovel claims, among other things, that the goods supplied by the Company do not conform to the standards specified in the contracts and claims damages in the amount of approximately RMB 105 million (approximately $16 million). The Company believes that Sinovel’s claims are without merit and it intends to defend these actions vigorously. Since the proceedings in this matter are still in the early technical review phase, the Company cannot reasonably estimate possible losses or range of losses at this time.

Other

The Company enters into long-term construction contracts with customers that require the Company to obtain performance bonds. The Company is required to deposit an amount equivalent to some or all the face amount of the performance bonds into an escrow account until the termination of the bond. When the performance conditions are met, amounts deposited as collateral for the performance bonds are returned to the Company. In addition, the Company has various contractual arrangements in which minimum quantities of goods or services have been committed to be purchased on an annual basis.

As of December 31, 2017, the Company had $0.2 million of restricted cash included in long-term assets. These amounts included in restricted cash primarily represent deposits to secure letters of credit for various supply contracts. These deposits are held in interest bearing accounts.

During the nine months ended December 31, 2017, the Company received $1.0 million related to the achievement of certain milestones following the previous sale of the Company's minority interest in Blade Dynamics Limited.

On September 25, 2017, the Company acquired ITC for a purchase price of approximately $3.8 million, consisting of $0.1 million in cash and the AMSC Shares. The Company paid certain selling stockholders the Make Whole Payment given that the value of the AMSC Shares sold was less than the agreed upon purchase price. The amount of this payment, which was made on January 5, 2018, was $0.7 million and settled the related contingent liability. See Note 4, “Acquisitions and Related Goodwill” for further discussion.