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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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