Financial Instruments - Summary of Valuation of Short-term Investments and Financial Instruments (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities, current	$ 2.6	$ 4.4
Marketable securities, noncurrent	3.3	2.9
Quoted Prices in Active Markets (Level 1)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities, noncurrent	2.0	0.2
Significant Other Observable Inputs (Level 2)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities, current	2.6	4.4
Marketable securities, noncurrent	$ 1.3	$ 2.7

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Amount of investment in marketable security, classified as current.

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Amount of investment in marketable security, classified as noncurrent.

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