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Acquisitions - Narrative (Details) $ / shares in Units, $ in Thousands |  | 3 Months Ended | 12 Months Ended
--- | --- | --- | ---
Jan. 17, 2018 USD ($) customer $ / shares | Mar. 30, 2019 USD ($) $ / shares | Mar. 31, 2018 USD ($) | Dec. 29, 2018 USD ($) $ / shares
Business Acquisition [Line Items] |  |  |  |
Common stock, par value (in dollars per share) | $ / shares |  | $ 0.01 |  | $ 0.01
Non-cash inventory charges |  | $ 0 | $ 17,896 |
Cash, net of cash acquired |  | 775 | 306,487 |
Non-cash, fair value of commitment to purchase non-controlling interest |  | $ 0 | 9,000 |
Inventory amortization period |  | 5 months |  |
IXYS Corporation |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Number of customers | customer | 3,500 |  |  |
Common stock, par value (in dollars per share) | $ / shares | $ 0.01 |  |  |
Share price (in dollars per share) | $ / shares | $ 23 |  |  |
Share exchange ratio | 0.1265 |  |  |
Share price (in dollars per share) | $ / shares | $ 207.5 |  |  |
Consideration excluding value of stock options converted | $ 814,800 |  |  |
Cash | 380,600 |  |  |
Littelfuse stock | 434,192 |  |  |
Value of options converted | 41,700 |  |  |
Consideration transferred | 856,500 |  |  |
Receivables | 49,100 |  |  |
Acquisition related costs |  |  |  | $ 10,200
Cash, net of cash acquired | $ 302,865 |  |  |
Other | Operating Income (Loss) |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Allocated share based compensation |  |  | 4,500 |
Acquisition related costs |  |  | 38,600 |
Inventory adjustment |  |  | 17,900 |
Employee Stock Option | IXYS Corporation |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Allocated share based compensation |  |  | 5,900 |
Employee Stock Option | IXYS Corporation | Selling, General and Administrative Expenses |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Allocated share based compensation |  |  | $ 4,500 |

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- Definition The fair value as of the acquisition-date of the commitment to purchase noncontrolling interest in the acquiree in a business combination. + References No definition available. + Details
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- Definition Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer, but excluding the value of stock options converted. + References No definition available. + Details
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- Definition Represents the value of stock options converted to company’s stock options in a business acquisition. + References No definition available. + Details
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- Definition The aggregate expense charged against earnings to allocate the cost of inventory previously stepped-up in cost basis in a business acquisition. + References No definition available. + Details
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- Definition Price of a single share of a number of saleable stocks paid or offered to be paid in a business combination. + References No definition available. + Details
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- Definition This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 25 -Paragraph 23 -URI http://asc.fasb.org/extlink&oid=84229725&loc=d3e1043-128460 + Details
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- Definition Amount due from customers or clients for goods or services, including trade receivables, that have been delivered or sold in the normal course of business, and amounts due from others, including related parties expected to be converted to cash, sold or exchanged within one year or the normal operating cycle, if longer, acquired at the acquisition date. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=84161108&loc=d3e4845-128472 + Details
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