Amortizable Intangible Assets (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 1,030,351	$ 901,843
Accumulated Amortization	(463,813)	(405,661)
Net Carrying Value	566,538	496,182
Purchased customer accounts
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	1,005,031	876,552
Accumulated Amortization	(439,623)	(381,615)
Net Carrying Value	565,408	494,937
Weighted Average Life (years)	14 years 10 months 24 days	14 years 10 months 24 days
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	25,320	25,291
Accumulated Amortization	(24,190)	(24,046)
Net Carrying Value	$ 1,130	$ 1,245
Weighted Average Life (years)	7 years 2 months 12 days	7 years 2 months 12 days