Percentage points added to the federal funds rate to compute the base rate

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Percentage points added to the Eurodollar rate on the debt instrument.

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Consolidated Leverage Ratio to remain compliant with credit agreement.

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Temporarily increased consolidated leverage ratio upon completion of an acquisition.

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Dollar amount threshold to qualify as an acquisition to trigger a temporary increase in the consolidated leverage ratio.

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Early repayment of debt due in 2022

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Early repayment of debt due in 2023

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Term loan principal repayment rate, increased

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Term loan principal repayment rate, initial

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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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Amount of unamortized debt discount (premium) and debt issuance costs.

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The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Weighted average interest rate of long-term debt outstanding calculated over time.

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Weighted average interest rate of long-term debt outstanding calculated at point in time.

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The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of uncollateralized debt obligations (with maturities initially due after one year or beyond the operating cycle if longer).

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Debt (Detail) - USD ($)			3 Months Ended	6 Months Ended
Debt (Detail) - USD ($)	Jun. 30, 2021	Jan. 06, 2020	Jun. 30, 2021	Jun. 30, 2021	Dec. 31, 2020	Dec. 01, 2020	Nov. 01, 2019
Debt Disclosure [Line Items]
Term loan principal repayment rate, initial	1.25%		1.25%	1.25%
Term loan principal repayment rate, increased	2.50%		2.50%	2.50%
Weighted-average interest rate over time			1.45%	1.45%
Weighted-average interest rate at point in time	1.40%		1.40%	1.40%
Consolidated leverage ratio	3.50		3.50	3.50
Consolidated leverage ratio increased	4.00		4.00	4.00
Qualified acquisition amount	$ 250,000,000.0		$ 250,000,000.0	$ 250,000,000.0
Long-term debt	753,327,000		753,327,000	753,327,000	$ 798,118,000
Unamortized debt issuance cost	1,700,000		1,700,000	1,700,000	$ 1,900,000
Livermore Software Technology Corporation
Debt Disclosure [Line Items]
Unsecured debt							$ 500,000,000.0
Early debt repayment	26,000,000.0	$ 75,000,000.0
Early repayment of debt due in 2022		25,000,000.0
Early repayment of debt due in 2023		$ 50,000,000.0
Analytical Graphics, Inc.
Debt Disclosure [Line Items]
Unsecured debt						$ 375,000,000.0
Early debt repayment	19,000,000.0
Early repayment of debt due in 2022	18,800,000		18,800,000	18,800,000
Early repayment of debt due in 2023	200,000		200,000	200,000
Revolving credit facility
Debt Disclosure [Line Items]
Line of credit, maximum borrowing capacity	500,000,000.0		500,000,000.0	500,000,000.0
Outstanding borrowings under the credit agreement	0		0	0
Letters of credit
Debt Disclosure [Line Items]
Line of credit, maximum borrowing capacity	$ 50,000,000.0		$ 50,000,000.0	$ 50,000,000.0
Base rate
Debt Disclosure [Line Items]
Debt instrument, basis spead on federal funds rate				0.50%
Debt instrument, basis spread on Eurodollar rate				1.00%
Base rate \| Minimum
Debt Disclosure [Line Items]
Debt instrument, basis spread on variable rate				0.125%
Base rate \| Maximum
Debt Disclosure [Line Items]
Debt instrument, basis spread on variable rate				0.75%
Eurodollar \| Minimum
Debt Disclosure [Line Items]
Debt instrument, basis spread on variable rate				1.125%
Eurodollar \| Maximum
Debt Disclosure [Line Items]
Debt instrument, basis spread on variable rate				1.75%