Commitments and Contingencies - Additional Information (Detail) (USD $)		1 Months Ended		9 Months Ended		12 Months Ended
	Dec. 31, 2001	Jan. 31, 2014 United States District Court for the Eastern District of Tennessee Retailer Action complaint	Aug. 09, 2007 United States District Court for the Eastern District of Tennessee Retailer Action complaint	Sep. 30, 2014 Minimum	Sep. 30, 2014 Maximum	Dec. 31, 2001 Contingent Promissory Note	Sep. 30, 2014 Contingent Promissory Note
Commitments and Contingencies [Line Items]
Acquired interest percentage	33.80%
Principal amount of contingent promissory note						$ 40,000,000
Promissory note term (years)						20 years
Contingent promissory note, maximum amount including interest							$ 96,000,000
Promissory note, maturity date						Dec. 21, 2021
Lease term, (years)				1 year	20 years
Number of putative class action antitrust complaints reversed		1
Number of putative class action antitrust complaints			5