Guarantees (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Guarantor Obligations [Line Items]
Total borrowings of the independents and affiliates subject to guarantee	$ 431,286
Guarantees related to borrowings, other assets	42,000	$ 35,000
Guarantees related to borrowings, other long-term liabilities	$ 42,000	$ 35,000
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