Guarantees (Detail) $ in Millions	6 Months Ended
Jun. 30, 2017 USD ($)
Guarantor Obligations [Line Items]
Total borrowings of the independents and affiliates subject to guarantee	$ 499.2
Guarantees related to borrowings, other assets	$ 53.0
Minimum [Member]
Guarantor Obligations [Line Items]
Guaranteed obligations maturity (in years)	1 year
Maximum [Member]
Guarantor Obligations [Line Items]
Guaranteed obligations maturity (in years)	6 years

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=82913245&loc=d3e12069-110248

Name:	us-gaap_GuaranteeObligationsMaximumExposure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant