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Long Term Debt - Additional Information (Detail) - USD ($) |  | 6 Months Ended |  |
--- | --- | --- | --- | ---
Jul. 31, 2018 | Dec. 31, 2018 | Dec. 31, 2017 | [1] | Jun. 30, 2018 | Dec. 23, 2016
Debt Instrument [Line Items] |  |  |  |  |  |
Aggregate principal amount of loan |  | $ 275,300,000 |  | $ 10,000,000 |  |
Long term debt, net |  | 273,300,000 |  | $ 9,300,000 | [1] |
Principal repayment |  | 75,000,000 | $ 56,000,000 |  |  |
Revolving Credit Facility [Member] |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Principal repayment |  | 75,000,000 |  |  |  |
Additional borrowings |  | $ 50,000,000 |  |  |  |
Revolving Credit Facility [Member] | Amendment to Credit Agreement [Member] |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Aggregate principal amount of loan | $ 300,000,000 |  |  |  |  |
Upfront fees | 1,800,000 |  |  |  |  |
Debt issuance costs | 300,000 |  |  |  |  |
Long term debt, net | 273,300,000 |  |  |  |  |
Scheduled principal payments prior to maturity date | $ 0 |  |  |  |  |
Revolving Credit Facility [Member] | Counsyl Inc [Member] | Amendment to Credit Agreement [Member] |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Loan agreement, maturity date | Jul. 31, 2023 |  |  |  |  |
Loans maximum borrowing capacity | $ 350,000,000 |  |  |  |  | $ 300,000,000
[1] | Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.

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