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Summary of Significant Accounting Policies - Additional Information (Detail) | 3 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Dec. 31, 2018 USD ($) | Mar. 31, 2019 USD ($) director shares | Mar. 31, 2018 USD ($) shares | Mar. 31, 2017 USD ($) shares | Apr. 01, 2018 USD ($)
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |
Intangible assets, net |  | $ 174,400,000 | $ 12,300,000 |  |
Goodwill |  | $ 201,100,000 | $ 4,900,000 |  |
Ownership interest rate percentage (as percent) |  | 100.00% |  |  |
Impairment |  | $ 4,600,000 |  |  |
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life |  | 11 years 8 months | 6 years 1 month |  |
Impairment |  | $ 2,600,000 | $ 0 | $ 0 |
Equity awards vested percentage after first year |  | 25.00% |  |  |
Equity awards vested percentage after second year |  | 25.00% |  |  |
Equity awards vested percentage after third year |  | 50.00% |  |  |
Deferred income taxes assets |  | $ 1,092,900,000 | 29,900,000 |  |
Deferred tax assets, valuation allowance |  | 267,600,000 | 129,600,000 |  |
Other assets |  | 2,900,000 | 4,700,000 |  |
Cumulative effect of new accounting principle in period of adoption |  |  |  |  | $ 1,160,300,000
Discrete tax benefit | $ 1,800,000 |  |  |  |
Asset impairments |  | $ 15,900,000 | $ 0 | $ 0 |
Accounting Standards Update 2016-16 [Member] |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |
Deferred income taxes assets |  |  |  |  | 1,313,000,000
Deferred tax assets, valuation allowance |  |  |  |  | 148,200,000
Other assets |  |  |  |  | 4,500,000
Restricted Stock Units (RSUs) [Member] |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |
Potential diluted common shares outstanding | shares |  | 0 | 0 | 0 |
Contingent Shares Not Expected To Vest [Member] |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |
Potential diluted common shares outstanding | shares |  | 2,200,000 | 1,600,000 | 1,800,000 |
Other Businesses |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |
Goodwill |  |  | $ 4,600,000 |  |
Impairment |  | $ 4,600,000 | 0 | $ 0 |
Impairment |  | 2,200,000 |  |  |
Asset impairments |  | $ 12,900,000 | 0 | 0 |
AICF Funding |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |
Ownership interest rate percentage (as percent) |  | 0.00% |  |  |
Retained Earnings [Member] | Accounting Standards Update 2016-16 [Member] |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |
Cumulative effect of new accounting principle in period of adoption |  |  |  |  | $ 1,160,300,000
AICF Funding |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |
Number of directors appointed by Company | director |  | 3 |  |  |
AICF Funding | New South Wales, Australia [Member] |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |
Number of directors appointed by NSW government | director |  | 2 |  |  |
Other Accrued Liabilities [Member] |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |
Prior period reclassification adjustment |  |  |  | (2,700,000) |
Income Tax Payable |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |
Prior period reclassification adjustment |  |  |  | $ 2,700,000 |
Adjustment |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |
Intangible assets, net |  |  | 12,300,000 |  |
Goodwill |  |  | $ 4,900,000 |  |
Selling, General and Administrative Expenses | Euro Denominated Debt [Member] |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |
Foreign currency translation gain |  | $ 2,900,000 |  |  |
Minimum [Member] |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life |  | 2 years |  |  |
Maximum [Member] |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life |  | 13 years |  |  |

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