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Contractual interest rate for funds borrowed, under the debt agreement.

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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 of long-term debt payable, sinking fund requirement, and other securities issued that are redeemable by holder at fixed or determinable price and date, maturing in remainder of current fiscal year.

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Amount of cash inflow from contractual arrangement with the lender, including but not limited to, letter of credit, standby letter of credit and revolving credit arrangements.

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Debt - Additional Information (Detail) - USD ($)	3 Months Ended	6 Months Ended
Debt - Additional Information (Detail) - USD ($)	Mar. 31, 2021	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Debt Instrument [Line Items]
Long-Term Debt, Maturity, Remainder of Fiscal Year			$ 0
3.75% Senior Notes due 2021 (issued: $500.0, August 2011)
Debt Instrument [Line Items]
Debt, stated interest rate		3.75%
Debt, face amount		$ 500,000,000.0	500,000,000.0	$ 500,000,000.0
Long-Term Debt, Maturity, Remainder of Fiscal Year		500,000,000		$ 500,000,000
Discretionary Line of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity		250,000,000
Borrowings outstanding	$ 0	$ 0	$ 0