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Income Taxes - Additional Information (Detail) - USD ($) | 3 Months Ended | 6 Months Ended | 12 Months Ended
--- | --- | --- | ---
Dec. 31, 2017 | Jun. 30, 2018 | Dec. 31, 2017 | Jun. 30, 2019 | Jun. 30, 2018 | Jun. 30, 2017
Income Tax Contingency [Line Items] |  |  |  |  |  |
U.S. federal statutory rate |  | 21.00% | 35.00% | 21.00% | 28.10% | 35.00%
Tax Act, incomplete accounting, provisional adjustments | $ (32,600,000) |  |  |  |  |
Earnings per share increase | $ 0.45 |  |  |  |  |
Tax Act, limitation on deduction of executive compensation |  |  |  | $ 1,000,000.0 |  |
Tax Act, incomplete accounting, transition tax for accumulated foreign earnings, provisional income tax expense |  |  |  | 0 |  |
Amount of valuation allowance increased (decreased) |  | $ (2,700,000) |  | 1,100,000 | $ (2,700,000) |
Net deferred tax liabilities |  | 109,500,000 |  | 185,600,000 | 109,500,000 |
Deferred tax assets |  | 90,000,000.0 |  | 141,900,000 | 90,000,000.0 |
Excess tax benefits attributable to deferred tax asset |  | 44,600,000 |  | 85,700,000 | 44,600,000 |
Valuation allowance offset amount |  | 37,800,000 |  | 38,900,000 | 37,800,000 |
Deferred tax liability not recognized, Amount of unrecognized deferred tax liability, undistributed earnings of foreign subsidiaries |  | $ 0 |  |  | $ 0 |
Cumulative effect |  |  |  | 0 |  |
Prior to the adoption of Statement 123(R) [Member] | UTAH [Member] |  |  |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |  |  |
Excess tax benefits attributable to deferred tax asset |  |  |  | 8,300,000 |  |
Valuation allowance offset amount |  |  |  | 8,300,000 |  |
Assurex [Member] |  |  |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |  |  |
Net deferred tax liabilities |  |  |  | 67,600,000 |  |
Deferred tax assets |  |  |  | $ 60,700,000 |  |
State Tax Authority [Member] | Earliest Tax Year [Member] | State of New Jersey [Member] |  |  |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |  |  |
Tax year being audited in income tax examination |  |  |  | 2013 |  |
State Tax Authority [Member] | Earliest Tax Year [Member] | City of New York [Member] |  |  |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |  |  |
Tax year being audited in income tax examination |  |  |  | 2014 |  |
State Tax Authority [Member] | Latest Tax Year [Member] | State of New Jersey [Member] |  |  |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |  |  |
Tax year being audited in income tax examination |  |  |  | 2017 |  |
State Tax Authority [Member] | Latest Tax Year [Member] | City of New York [Member] |  |  |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |  |  |
Tax year being audited in income tax examination |  |  |  | 2016 |  |
Foreign Tax Authority [Member] | Earliest Tax Year [Member] | Federal Ministry of Finance, Germany [Member] |  |  |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |  |  |
Tax year being audited in income tax examination |  |  |  | 2013 |  |
Foreign Tax Authority [Member] | Earliest Tax Year [Member] | Switzerland Federal Tax Administration [Member] |  |  |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |  |  |
Tax year being audited in income tax examination |  |  |  | 2015 |  |
Foreign Tax Authority [Member] | Latest Tax Year [Member] | Federal Ministry of Finance, Germany [Member] |  |  |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |  |  |
Tax year being audited in income tax examination |  |  |  | 2015 |  |
Foreign Tax Authority [Member] | Latest Tax Year [Member] | Switzerland Federal Tax Administration [Member] |  |  |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |  |  |
Tax year being audited in income tax examination |  |  |  | 2016 |  |

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