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.