Significant Accounting Policies (Policies)	6 Months Ended
Sep. 30, 2016
Accounting Policies [Abstract]
Basis of Accounting, Policy [Policy Text Block]	The accompanying interim unaudited condensed consolidated financial statements have been prepared in accordance with the instructions to Form 10-Q and do not include all of the information and footnotes required by accounting principles generally accepted in the United States of America for complete financial statements. The unaudited condensed consolidated financial statements include the accounts of IXYS Corporation and its wholly-owned subsidiaries. The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and judgments that affect the amounts reported in the financial statements and accompanying notes. Some of the accounting estimates that require significant judgments by management include, but are not limited to, revenue reserves, inventory valuation, accounting for income taxes and allocation of purchase price in business combinations. All significant intercompany transactions have been eliminated in consolidation. All adjustments of a normal recurring nature that, in the opinion of management, are necessary for a fair statement of the results for the interim periods have been made. The condensed consolidated balance sheet as of March 31, 2016 has been derived from our audited consolidated balance sheet as of that date. It is recommended that the interim financial statements be read in conjunction with our audited consolidated financial statements and notes thereto for the fiscal year ended March 31, 2016, or fiscal 2016, contained in our Annual Report on Form 10-K. Interim results are not necessarily indicative of the operating results expected for later quarters or the full fiscal year. Our fiscal year end is March 31. References to any numerically identified year preceded by the word “fiscal” are references to the year ending on March 31 of such numerically identified year.
New Accounting Pronouncements, Policy [Policy Text Block]	In May 2014, Financial Accounting Standards Board, or FASB, issued a new standard on the recognition of revenue from contracts with customers, which includes a single set of rules and criteria for revenue recognition to be used across all industries. The revenue standard’s core principle is built on the contract between a vendor and a customer for the provision of goods and services. It attempts to depict the exchange of rights and obligations between the parties in the pattern of revenue recognition based on the consideration to which the vendor is entitled. To accomplish this objective, the standard requires five basic steps: identify the contract with the customer, identify the performance obligations in the contract, determine the transaction price, allocate the transaction price to the performance obligations in the contract and recognize revenue when or as the entity satisfies a performance obligation. For public companies, this standard is effective for annual reporting periods beginning after December 15, 2017, including interim periods during the annual period. Early adoption is permitted for annual periods commencing after December 15, 2016. Two d ifferent transition methods are available: full retrospective method and a modified retrospective approach. We are currently evaluating the impact of the adoption of the standard on our consolidated financial statements including selection of the transition method. In July 2015, FASB issued an amendment to modify the inventory measurement guidance in Topic 330, Inventory , for inventory that is measured using the methods other than last-in, first-out, or LIFO, and the retail inventory method. It requires that an entity measure inventory within the scope of this update at the lower of cost and net realizable value. It eliminated the guidance in Topic 330 that required a reporting entity measuring inventory at the lower of cost or market to consider the replacement cost of inventory and the net realizable value of inventory less an approximately normal profit margin along with net realizable value in determining the market value. The guidance will be effective for annual reporting periods beginning after December 15, 2016, and interim periods during the annual period. The new standard is required to be applied prospectively with earlier application permitted as of the beginning of an interim or annual reporting period. We do not expect this change to have a significant impact on our consolidated financial statements. In January 2016, the FASB issued authoritative guidance that modifies how entities measure equity investments and present changes in the fair value of financial liabilities. Under the new guidance, entities will have to measure equity investments that do not result in consolidation and are not accounted under the equity method at fair value and recognize any changes in fair value in net income unless the investments qualify for the new practicality exception. A practicality exception will apply to those equity investments that do not have a readily determinable fair value and do not qualify for the practical expedient to estimate fair value under Accounting Standards Codification, or ASC 820, Fair Value Measurements , and as such these investments may be measured at cost. This guidance is effective for financial statements issued for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. We are currently evaluating the impact of this standard on our consolidated financial statements. In February 2016, FASB issued amended guidance for lease arrangements, which requires lessees to recognize the followings for all leases with terms longer than 12 months: a lease liability, which is a lessee’s obligation to make lease payments arising from a lease, measured on a discounted basis and a right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. The amendment is effective for financial statements issued for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted. We are currently evaluating the impact of this amended guidance on our consolidated financial statements. In March 2016, FASB issued amended guidance to simplify the transition to the equity method of accounting. This standard eliminates the requirement that when an existing cost method investment qualifies for use of the equity method, an investor must restate its historical financial statements, as if the equity method had been used during all previous periods. Additionally, any unrealized gain or loss in accumulated other comprehensive income (loss) will be recognized through earnings at the point an investment qualifies for the equity method. The amended guidance is effective for financial statements issued for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2016. It should be applied prospectively. Early adoption is permitted. We are currently evaluating the impact of this amended guidance on our consolidated financial statements. In March, 2016, FASB issued amended guidance which simplifies several aspects of the accounting for employee share-based payment awards, including forfeitures, employer tax withholding on share-based compensation and excess tax benefits or deficiencies. The amended guidance also clarifies the statement of cash flows presentation for share-based awards. The guidance is effective for financial statements issued for fiscal years beginning after December 15, 2016, and interim periods within those fiscal years. Early adoption is permitted in any interim or annual period for which financial statements have not yet been issued or have not been made available for issuance. We are currently evaluating the impact of this amended guidance on our consolidated financial statements. In June 2016, FASB issued amended guidance which replaces the incurred loss impairment methodology in the current guidance with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. The amendments affect financial assets and net investment in leases that are not accounted for at fair value through net income. The new guidance is effective for financial statements issued for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is allowed as of the fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. We are currently evaluating the impact of this amended guidance on our consolidated financial statements. In August 2016, FASB issued amended guidance which addresses the classification of cash flows related to debt prepayment or extinguishment costs, settlement of zero-coupon debt instruments or other debt instruments with coupon rates that are insignificant in relation to the effective interest rate of the borrowing, contingent consideration payments made after a business combination, proceeds from the settlement of insurance claims, proceeds from the settlement of corporate-owned life insurance including bank-owned life insurance, distributions received from equity method investees and beneficial interests in securitization transactions. The guidance also clarifies how the predominance principle should be applied when cash receipts and cash payments have aspects of more than one class of cash flows. The guidance is effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. We do not expect this change to have a significant impact on our consolidated financial statements.

In May 2014, Financial Accounting Standards Board, or FASB, issued a new standard on the recognition of revenue from contracts with customers, which includes a single set of rules and criteria for revenue recognition to be used across all industries. The revenue standard’s core principle is built on the contract between a vendor and a customer for the provision of goods and services. It attempts to depict the exchange of rights and obligations between the parties in the pattern of revenue recognition based on the consideration to which the vendor is entitled. To accomplish this objective, the standard requires five basic steps: identify the contract with the customer, identify the performance obligations in the contract, determine the transaction price, allocate the transaction price to the performance obligations in the contract and recognize revenue when or as the entity satisfies a performance obligation. For public companies, this standard is effective for annual reporting periods beginning after December 15, 2017, including interim periods during the annual period. Early adoption is permitted for annual periods commencing after December 15, 2016. Two d

ifferent transition methods are available:

full retrospective method and a modified retrospective

approach. We are currently evaluating the impact of the adoption of the standard on our consolidated financial statements including selection of the transition method.

In July 2015, FASB issued an amendment to modify the inventory measurement guidance in Topic 330,

Inventory

, for inventory that is measured using the methods other than last-in, first-out, or LIFO, and the retail inventory method. It requires that an entity measure inventory within the scope of this update at the lower of cost and net realizable value. It eliminated the guidance in Topic 330 that required a reporting entity measuring inventory at the lower of cost or market to consider the replacement cost of inventory and the net realizable value of inventory less an approximately normal profit margin along with net realizable value in determining the market value. The guidance will be effective for annual reporting periods beginning after December 15, 2016,

and interim periods during the annual period. The new standard is required to be applied prospectively with earlier application permitted as of the beginning of an interim or annual reporting period. We do not expect this change to have a significant impact on our consolidated financial statements.

In January 2016, the FASB issued authoritative guidance that modifies how entities measure equity investments and present changes in the fair value of financial liabilities. Under the new guidance, entities will have to measure equity investments that do not result in consolidation and are not accounted under the equity method at fair value and recognize any changes in fair value in net income unless the investments qualify for the new practicality exception. A practicality exception will apply to those equity investments that do not have a readily determinable fair value and do not qualify for the practical expedient to estimate fair value under Accounting Standards Codification, or ASC 820,

Fair Value Measurements

, and as such these investments may be measured at cost. This guidance is effective for financial statements issued for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. We are currently evaluating the impact of this standard on our consolidated financial statements.

In February 2016, FASB issued amended guidance for lease arrangements, which requires lessees to recognize the followings

for all leases with terms longer than 12 months: a lease liability, which is a lessee’s obligation to make lease payments arising from a lease, measured on a discounted basis and a right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. The amendment is effective for financial statements issued for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted.

We are currently evaluating the impact of this amended guidance on our consolidated financial statements.

In March 2016, FASB issued amended guidance to simplify the transition to the equity method of accounting. This standard eliminates the requirement that when an existing cost method investment qualifies for use of the equity method, an investor must restate its historical financial statements, as if the equity method had been used during all previous periods. Additionally, any unrealized gain or loss in accumulated other comprehensive income (loss) will be recognized through earnings at the point an investment qualifies for the equity method. The amended guidance is effective for financial statements issued for

fiscal years, and interim periods within those fiscal years, beginning after December 15, 2016. It should be applied prospectively. Early adoption

is permitted. We are currently evaluating the impact of

this amended guidance on our consolidated financial statements.

In March, 2016, FASB issued amended guidance which simplifies several aspects of the accounting for

employee share-based payment awards, including

forfeitures, employer tax withholding on share-based compensation and excess tax benefits or deficiencies.

The amended guidance also clarifies the statement of cash flows presentation for share-based awards. The guidance is effective for financial statements issued for fiscal years beginning after December 15, 2016, and interim periods within those fiscal years. Early adoption is permitted in any interim or annual period for which financial statements have not yet been issued or have not been made available for issuance.

We are currently evaluating the impact of this amended guidance on our consolidated financial statements.

In June 2016, FASB issued amended guidance which replaces the incurred loss impairment methodology in the current guidance with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. The amendments affect financial assets and net investment in leases that are not accounted for at fair value through net income. The new guidance is effective for financial statements issued for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is allowed as of the fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. We are currently evaluating the impact of this amended guidance on our consolidated financial statements.

In August 2016, FASB issued amended guidance which addresses the classification of cash flows related to debt prepayment or extinguishment costs, settlement of zero-coupon debt instruments or other debt instruments with coupon rates that are insignificant in relation to the effective interest rate of the borrowing, contingent consideration payments made after a business combination, proceeds from the settlement of insurance claims, proceeds from the settlement of corporate-owned life insurance including bank-owned life insurance, distributions received from equity method investees and beneficial interests in securitization transactions. The guidance also clarifies how the predominance principle should be applied when cash receipts and cash payments have aspects of more than one class of cash flows. The guidance is effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. We do not expect this change to have a significant impact on our consolidated financial statements.