Intangible Assets - Additional Information (Detail)	9 Months Ended	12 Months Ended
	Sep. 30, 2012	Dec. 31, 2011
Long-term franchise agreements and contracts [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average amortization period of acquired intangible assets	6 years 11 months 2 days	22 years 4 months 4 days
Customer lists [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average amortization period of acquired intangible assets	9 years 5 months 0 days	6 years 10 months 23 days
Other [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average amortization period of acquired intangible assets	40 years	40 years