Other Intangible Assets, Net (Schedule of Finite-Lived Intangible Assets by Major Class) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Gross	$ 793,823		$ 793,823		$ 798,584
Accumulated Amortization	(459,460)		(459,460)		(422,955)
Net	334,363		334,363		375,629
Amortization of Intangible Assets	14,200		42,500	$ 45,900
Impairment of intangible assets	0	$ 0	0	35,600
Client lists
Finite-Lived Intangible Assets [Line Items]
Gross	640,155		640,155		645,770
Accumulated Amortization	(364,295)		(364,295)		(340,168)
Net	275,860		275,860		305,602
Impairment of intangible assets				$ 32,300
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Gross	26,755		26,755		26,409
Accumulated Amortization	(20,233)		(20,233)		(16,249)
Net	6,522		6,522		10,160
Tradenames and licenses
Finite-Lived Intangible Assets [Line Items]
Gross	126,913		126,913		126,405
Accumulated Amortization	(74,932)		(74,932)		(66,538)
Net	$ 51,981		$ 51,981		$ 59,867