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