Customer Lists and Other Identifiable Intangible Assets, Net - Additional Information (Detail) - Customer Lists and Other Identifiable Intangible Assets [Member]	9 Months Ended
Sep. 30, 2018
Minimum [Member]
Finite Lived Intangible Assets [Line Items]
Estimated useful life	12 years
Maximum [Member]
Finite Lived Intangible Assets [Line Items]
Estimated useful life	20 years

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_FiniteLivedIntangibleAssetsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration