Income Taxes - Additional Information (Detail) $ in Millions	6 Months Ended
	Jun. 30, 2018 USD ($)
Income Tax Disclosure [Abstract]
Reserve for uncertain tax positions	$ 7.4
Uncertain tax position reduction in deferred tax assets	4.6
Uncertain tax positions long term liabilities	2.8
Tax cuts and jobs act, incomplete accounting, transition tax for accumulated foreign earnings, provisional income tax expense	0.2
Deemed repatriation of foreign earnings	$ 0.0