Marketable Securities - Schedule of Marketable Securities (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Schedule Of Available For Sale Securities [Line Items]
Market value, available for sale securities, current	$ 2.6	$ 4.4
Market value, available for sale securities, noncurrent	3.3	2.9
Non Current Assets
Schedule Of Available For Sale Securities [Line Items]
Market value, available for sale securities, noncurrent	3.3	2.9
Cost basis	3.3	2.9
Current Assets
Schedule Of Available For Sale Securities [Line Items]
Market value, available for sale securities, current	2.6	4.4
Cost basis	$ 2.6	$ 4.4

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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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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