Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Dec. 31, 2017	Jun. 30, 2018
Income Tax Contingency [Line Items]
Net tax expense related to tax law change	$ 1.1
Reversal of liability for an uncertain tax position		$ 43.3
U.S corporate income tax rate	35.00%	21.00%
ASU 2016-16 [Member]
Income Tax Contingency [Line Items]
Cumulative effect of applying new standard as adjustment to opening retained earnings		$ 17.4

The net income tax effect on the entity of adopting the provisions of the U.S. Tax Cuts and Jobs Act of 2017.

No definition available.

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- Definition

Amount of the cumulative effect on retained earnings net of related income tax effect.

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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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.

+ References

No definition available.

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Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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