Significant Accounting Policies (Policies)	9 Months Ended
Dec. 31, 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, 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, Fair Value Measurements , or ASC 820, 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 following 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 October 2016, FASB issued amended guidance which requires an entity to recognize the income tax consequences of an intra-entity transfer of an asset, other than inventory, when the transfer occurs. This eliminates the current exception for all intra-entity transfers of an asset other than inventory that requires deferral of the tax effects until the asset is sold to a third party or otherwise recovered through use. The guidance will be effective for the Company for fiscal years beginning after December 15, 2017, including interim reporting periods within those annual reporting periods. Early adoption is permitted in the first interim period only. The amendments should be applied on a modified retrospective basis through a cumulative-effect adjustment directly to retained earnings as of the beginning of the period of adoption. We are in the process of evaluating the impacts of the adoption of this amendment. In November 2016, FASB issued amended guidance which requires that a statement of cash flows explain the change during the period in the total of cash, cash equivalents, and restricted cash. Therefore, restricted cash should be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. The guidance is effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years, and will be applied on a retrospective basis. We have adopted the guidance on a retrospective basis from the quarter ended December 31, 2016. In our unaudited condensed consolidated statements of cash flow statements for the nine month periods ended December 31, 2016 and 2015, the beginning balances of cash and cash equivalents included restricted cash of $277,000 and $266,000 in the respective periods and the ending balances of cash and cash equivalents included restricted cash of $1.3 million and $722,000 in the respective periods. If we had not adopted the amended guidance, our unaudited condensed consolidated statements of cash flows for the nine month periods ended December 31, 2016 and 2015 would have shown a decrease of $1.0 million and $357,000, respectively, in the change in restricted cash under cash flows from investing activities.

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.

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.

January

2016,

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,

Fair Value Measurements

, or ASC

820,

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.

February

2016,

FASB issued amended guidance for lease arrangements, which requires lessees to recognize the following

for all leases with terms longer than

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.

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.

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.

October

2016,

FASB issued amended guidance which requires an entity to recognize the income tax consequences of an intra-entity transfer of an asset, other than inventory, when the transfer occurs. This eliminates the current exception for all intra-entity transfers of an asset other than inventory that requires deferral of the tax effects until the asset is sold to a

third

party or otherwise recovered through use. The guidance will be effective for the Company for fiscal years beginning after

December

15,

2017,

including interim reporting periods within those annual reporting periods. Early adoption is permitted in the

first

interim period only. The amendments should be applied on a modified retrospective basis through a cumulative-effect adjustment directly to retained earnings as of the beginning of the period of adoption.

We are in the process of evaluating the impacts of the adoption of this amendment.

November

2016,

FASB issued amended guidance which requires that a statement of cash flows explain the change during the period in the total of cash, cash equivalents, and restricted cash. Therefore, restricted cash should be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. The guidance is effective for fiscal years beginning after

December

15,

2017,

and interim periods within those fiscal years, and will be applied on a retrospective basis. We have adopted the guidance on a retrospective basis from the quarter ended

December

31,

2016.

In our unaudited condensed consolidated statements of cash flow statements for the

nine

month periods ended

December

31,

2016

and

2015,

the beginning balances of cash and cash equivalents included restricted cash of

$277,000

and

$266,000

in the respective periods and the ending balances of cash and cash equivalents included restricted cash of

$1.3

million and

$722,000

in the respective periods. If we had not adopted the amended guidance, our unaudited condensed consolidated statements of cash flows for the

nine

month periods ended

December

31,

2016

and

2015

would have shown a decrease of

$1.0

million and

$357,000,

respectively, in the change in restricted cash under cash flows from investing activities.