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Income Taxes - Additional Information (Detail) - USD ($) | 6 Months Ended | 12 Months Ended
--- | --- | ---
Jun. 30, 2018 | Dec. 31, 2017 | Jun. 30, 2018 | Jun. 30, 2017 | Jun. 30, 2016
Income Tax Contingency [Line Items] |  |  |  |  |
U.S. federal statutory rate | 21.00% | 35.00% | 28.10% | 35.00% | 35.00%
Tax Act, incomplete accounting, provisional adjustments |  |  | $ (32,000,000) |  |
Tax Act, incomplete accounting, provisional estimate revaluation of liability adjustments |  |  | 3,300,000 |  |
Tax Act, limitation on deduction of executive compensation | $ 1,000,000 |  |  |  |
Tax Act, incomplete accounting, transition tax for accumulated foreign earnings, provisional income tax expense | 0 |  |  |  |
Amount of valuation allowance increased (decreased) | (2,700,000) |  | (2,700,000) | $ 4,900,000 |
Net deferred tax liabilities | 109,500,000 |  | 109,500,000 | 177,700,000 |
Excess tax benefits attributable to deferred tax asset | 44,600,000 |  | 44,600,000 | 75,500,000 |
Valuation allowance offset amount | 37,800,000 |  | 37,800,000 | $ 40,500,000 |
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 |  | 8,300,000 |  |
Valuation allowance offset amount | 8,300,000 |  | 8,300,000 |  |
Assurex [Member] |  |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |  |
Net deferred tax liabilities | 66,300,000 |  | $ 66,300,000 |  |
Foreign Tax Authority [Member] |  |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |  |
Tax Act, incomplete accounting, provisional adjustments | $ 0 |  |  |  |
Foreign Tax Authority [Member] | Federal Ministry of Finance, Germany [Member] | Earliest Tax Year [Member] |  |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |  |
Tax year being audited in income tax examination |  |  | 2013 |  |
Foreign Tax Authority [Member] | Federal Ministry of Finance, Germany [Member] | Latest Tax Year [Member] |  |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |  |
Tax year being audited in income tax examination |  |  | 2015 |  |
Foreign Tax Authority [Member] | Canada Revenue Agency [Member] | Earliest Tax Year [Member] |  |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |  |
Tax year being audited in income tax examination |  |  | 2014 |  |
Foreign Tax Authority [Member] | Canada Revenue Agency [Member] | Latest Tax Year [Member] |  |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |  |
Tax year being audited in income tax examination |  |  | 2015 |  |
U.S. Tax Authority [Member] | IRS [Member] | Tax Year 2014 [Member] |  |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |  |
Tax year being audited in income tax examination |  |  | 2014 |  |
U.S. Tax Authority [Member] | IRS [Member] | Tax Year 2015 [Member] |  |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |  |
Tax year being audited in income tax examination |  |  | 2015 |  |
State Tax Authority [Member] | State of New Jersey [Member] | Earliest Tax Year [Member] |  |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |  |
Tax year being audited in income tax examination |  |  | 2013 |  |
State Tax Authority [Member] | State of New Jersey [Member] | Latest Tax Year [Member] |  |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |  |
Tax year being audited in income tax examination |  |  | 2017 |  |
State Tax Authority [Member] | State of Wisconsin [Member] | Earliest Tax Year [Member] |  |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |  |
Tax year being audited in income tax examination |  |  | 2014 |  |
State Tax Authority [Member] | State of Wisconsin [Member] | Latest Tax Year [Member] |  |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |  |
Tax year being audited in income tax examination |  |  | 2016 |  |

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