Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2018	Oct. 01, 2017	Dec. 31, 2017
Income Tax [Line Items]
Effective income tax rate		24.10%	34.80%
Effective income tax rate with noncontrolling interest		32.50%	38.80%
Provisional tax benefit related to re-measurement of net deferred tax liability	$ 1,900,000			$ 69,000,000
Uncertain tax positions	3,000,000	$ 3,000,000		2,400,000
Uncertain tax positions that would affect tax rate	3,000,000	3,000,000		$ 2,400,000
Change in uncertain tax positions, expected material impact on consolidated condensed financial statements	$ 0	$ 0
Earliest Tax Year [Member] | Internal Revenue Service (IRS) [Member]
Income Tax [Line Items]
Tax year open for examination		2002
Earliest Tax Year [Member] | State and Local Jurisdiction [Member]
Income Tax [Line Items]
Tax year open for examination		1998