Amortizable Intangible Assets - Amortizable Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Gross carrying value	$ 2,001,704	$ 1,959,207
Accumulated amortization	(1,068,830)	(1,042,439)
Net carrying value	932,874	916,768
Purchased Customer Accounts
Finite-Lived Intangible Assets [Line Items]
Gross carrying value	1,967,117	1,925,326
Accumulated amortization	(1,037,652)	(1,011,574)
Net carrying value	$ 929,465	$ 913,752
Weighted average life (years)	15 years	15 years
Non-compete Agreements
Finite-Lived Intangible Assets [Line Items]
Gross carrying value	$ 34,587	$ 33,881
Accumulated amortization	(31,178)	(30,865)
Net carrying value	$ 3,409	$ 3,016
Weighted average life (years)	4 years 7 months 6 days	4 years 7 months 6 days