Amortizable Intangible Assets - Amortizable Intangible Assets (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 1,384,689	$ 1,148,834
Accumulated Amortization	(600,047)	(529,946)
Net Carrying Value	784,642	618,888
Purchased customer accounts [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	1,355,550	1,120,719
Accumulated Amortization	(574,285)	(505,137)
Net Carrying Value	781,265	615,582
Weighted Average Life (years)	14 years 10 months 24 days	14 years 10 months 24 days
Non-compete agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	29,139	28,115
Accumulated Amortization	(25,762)	(24,809)
Net Carrying Value	$ 3,377	$ 3,306
Weighted Average Life (years)	6 years 9 months 18 days	7 years