Employer Sponsored Benefit Plans - Additional Information (Detail) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Contributions made by company to domestic pension plan	$ 1.2	$ 2.4
Minimum
Defined Benefit Plan Disclosure [Line Items]
Expected domestic pension plan cash contribution in current year	3.5	3.5
Maximum
Defined Benefit Plan Disclosure [Line Items]
Expected domestic pension plan cash contribution in current year	$ 4.0	$ 4.0