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Note 2 - Acquisitions (Details Textual) $ / shares in Units, $ in Thousands |  |  |  |  | 1 Months Ended | 3 Months Ended | 5 Months Ended | 6 Months Ended |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Jan. 17, 2018 USD ($) $ / shares | Jul. 07, 2017 USD ($) | Mar. 01, 2017 USD ($) | Feb. 28, 2017 USD ($) | Apr. 30, 2018 USD ($) | Jun. 30, 2018 USD ($) $ / shares | Jun. 30, 2018 USD ($) $ / shares | Jun. 30, 2018 USD ($) $ / shares | Jul. 01, 2017 USD ($) | Dec. 30, 2017 $ / shares | Dec. 31, 2016 USD ($) | Dec. 31, 2015 USD ($)
Common Stock, Par or Stated Value Per Share | $ / shares |  |  |  |  |  | $ 0.01 | $ 0.01 | $ 0.01 |  | $ 0.01 |  |
Share Price | $ / shares | $ 207.50 |  |  |  |  |  |  |  |  |  |  |
Inventory Charge Related to Step-up in Cost Basis |  |  |  |  |  |  |  | $ 36,927 |  |  |  |
Payments to Acquire Businesses, Net of Cash Acquired, Total |  |  |  |  |  |  |  | 310,487 | 14,172 |  |  |
Business Combination, Consideration Transferred, Commitment to Purchase Noncontrolling Interest |  |  |  |  |  |  |  |  | $ 9,000 |  |  |
Inventory, Amortization Period |  |  |  |  |  |  |  | 150 days |  |  |  |
Order or Production Backlog [Member] |  |  |  |  |  |  |  |  |  |  |  |
Finite-Lived Intangible Asset, Useful Life |  |  |  |  |  |  |  | 1 year |  |  |  |
Monolith [Member] |  |  |  |  |  |  |  |  |  |  |  |
Cost Method Investments |  |  |  |  |  |  |  |  |  |  | $ 3,500 | $ 3,500
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners |  |  |  |  |  |  |  |  |  |  |  | 12.00%
IXYS Corporation [Member] |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition, Share Price | $ / shares | $ 23 |  |  |  |  |  |  |  |  |  |  |
Business Acquisition, Share Exchange Ratio | 0.1265 |  |  |  |  |  |  |  |  |  |  |
Business Combination, Consideration Transferred, Excluding Value of Stock Options Converted | $ 814,800 |  |  |  |  |  |  |  |  |  |  |
Payments to Acquire Businesses, Gross | 380,600 |  |  |  |  |  |  |  |  |  |  |
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable | 434,192 |  |  |  |  |  |  |  |  |  |  |
Business Combination, Value of Stock Options Converted to Company’s Stock Options | 41,700 |  |  |  |  |  |  |  |  |  |  |
Business Combination, Consideration Transferred, Total | 856,500 |  |  |  |  |  |  |  |  |  |  |
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables | 49,100 |  |  |  |  |  |  |  |  |  |  |
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual |  |  |  |  |  | $ 100,200 | $ 186,500 |  |  |  |  |
Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual |  |  |  |  |  | 13,900 | $ 31,700 |  |  |  |  |
Business Combination, Step Up of Inventory at Acquisition Date | 36,900 |  |  |  |  |  |  |  |  |  |  |
Inventory Charge Related to Step-up in Cost Basis |  |  |  |  |  | 19,000 |  | $ 36,900 |  |  |  |
Payments to Acquire Businesses, Net of Cash Acquired, Total | 302,865 |  |  |  |  |  |  |  |  |  |  |
IXYS Corporation [Member] | Selling, General and Administrative Expenses [Member] |  |  |  |  |  |  |  |  |  |  |  |
Business Combination, Acquisition Related Costs |  |  |  |  |  | 800 |  | 11,000 |  |  |  |
IXYS Corporation [Member] | Employee Stock Option [Member] |  |  |  |  |  |  |  |  |  |  |  |
Allocated Share-based Compensation Expense, Total | $ 4,500 |  |  |  |  | $ 1,600 |  | $ 7,500 |  |  |  |
U.S. Sensor [Member] |  |  |  |  |  |  |  |  |  |  |  |
Payments to Acquire Businesses, Gross |  | $ 24,340 |  |  |  |  |  |  |  |  |  |
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables |  | 1,500 |  |  |  |  |  |  |  |  |  |
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Inventory |  | $ 1,600 |  |  |  |  |  |  |  |  |  |
Monolith [Member] |  |  |  |  |  |  |  |  |  |  |  |
Business Combination, Consideration Transferred, Total |  |  |  | $ 15,000 | $ 5,000 |  |  |  |  |  |  |
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables |  |  |  | $ 700 |  |  |  |  |  |  |  |
Business Acquisition, Percentage of Voting Interests Acquired |  |  |  | 62.00% | 19.00% |  |  |  |  |  |  |
Business Combination, Step Acquisition, Remaining Interest Percentage |  |  |  |  | 19.00% |  |  |  |  |  |  |
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, Low |  |  |  | $ 500 |  |  |  |  |  |  |  |
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High |  |  |  | 5,000 |  |  |  |  |  |  |  |
Business Combination, Step Acquisition, Equity Interest in Acquiree, Fair Value |  |  | $ 3,500 | 3,500 |  |  |  |  |  |  |  |
Payments to Acquire Businesses, Net of Cash Acquired, Total |  |  | 14,172 | 14,200 |  |  |  |  |  |  |  |
Business Combination, Consideration Transferred, Commitment to Purchase Noncontrolling Interest |  |  | 9,000 | 9,000 |  |  |  |  |  |  |  |
Business Combination, Consideration Transferred, Including Equity Interest in Acquiree Held Prior to Combination, Total |  |  | $ 26,672 | $ 26,700 |  |  |  |  |  |  |  |
Monolith [Member] | Stockholders of Monolith [Member] |  |  |  |  |  |  |  |  |  |  |  |
Business Combination, Consideration Transferred, Total |  |  |  |  | $ 4,000 |  |  |  |  |  |  |
IXYS Corporation [Member] |  |  |  |  |  |  |  |  |  |  |  |
Number of Customers | 3,500 |  |  |  |  |  |  |  |  |  |  |
Common Stock, Par or Stated Value Per Share | $ / shares | $ 0.01 |  |  |  |  |  |  |  |  |  |  |

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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 Fair value at acquisition-date of the assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interests issued by the acquirer, including but not limited to, instruments or interests issued or issuable in consideration for the business combination. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (g) -URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463 + Details
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- Definition This element represents the amount of earnings or loss of the acquiree since the acquisition date included in the consolidated income statement for the reporting period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(1) -URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463 + Details
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- Definition This element represents the amount of revenue of the acquiree since the acquisition date included in the consolidated income statement for the reporting period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(1) -URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463 + Details
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- Definition This element represents the amount of any measurement period adjustment (as defined) realized during the reporting period to inventory acquired in connection with a business combination for which the initial accounting was incomplete. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 4A -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=84161108&loc=SL65897772-128472 + Details
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