Goodwill and Other Intangible Assets - Schedule of Other Intangible Assets by Major Classification (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Intangible Assets By Major Class [Line Items]
Weighted- Average Amortization Period (in years)	15 years 7 months 6 days	15 years 9 months 18 days
Gross	$ 999,174	$ 979,299
Accumulated Amortization	(249,902)	(207,432)
Net Book Value	749,272	771,867
Customer base [Member]
Intangible Assets By Major Class [Line Items]
Weighted- Average Amortization Period (in years)	15 years 9 months 18 days	16 years 1 month 6 days
Gross	721,010	696,326
Accumulated Amortization	(242,355)	(194,836)
Net Book Value	478,655	501,490
Amortizable trade names [Member]
Intangible Assets By Major Class [Line Items]
Weighted- Average Amortization Period (in years)	6 years 8 months 12 days	6 years
Gross	15,671	21,980
Accumulated Amortization	(6,577)	(11,642)
Net Book Value	9,094	10,338
Noncompete agreements [Member]
Intangible Assets By Major Class [Line Items]
Weighted- Average Amortization Period (in years)	3 years 9 months 18 days	5 years
Gross	2,470	970
Accumulated Amortization	(970)	(954)
Net Book Value	1,500	16
Indefinite lived trade names [Member]
Intangible Assets By Major Class [Line Items]
Gross	260,023	260,023
Accumulated Amortization
Net Book Value	$ 260,023	$ 260,023