Amortizable Intangible Assets - Amortizable Intangible Assets (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 1,474,687		$ 1,428,426
Accumulated Amortization	(748,547)		(683,746)
Net Carrying Value	726,140		744,680
Purchased customer accounts
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	1,445,052		1,398,986
Accumulated Amortization	(720,728)		(656,799)
Net Carrying Value	$ 724,324		742,187
Weighted Average Life (Years)	15 years	15 years
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 29,635		29,440
Accumulated Amortization	(27,819)		(26,947)
Net Carrying Value	$ 1,816		$ 2,493
Weighted Average Life (Years)	6 years 9 months 18 days	6 years 9 months 18 days