Investments - Additional Information (Detail) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Restricted Cash and Investments [Member]
Schedule Of Investment Income Reported Amounts By Category [Line Items]
Long-term investments	$ 12.1	$ 12.1

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.

No definition available.

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