Other Intangible Assets, Net (Schedule of Finite-Lived Intangible Assets by Major Class) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Gross	$ 809,245		$ 809,245		$ 816,196
Accumulated Amortization	(458,190)		(458,190)		(437,378)
Net	351,055		351,055		378,818
Amortization of Intangible Assets	14,300	$ 15,400	28,600	$ 32,000
Impairment of intangible assets	0	$ 35,600	0	35,600
Client lists
Finite-Lived Intangible Assets [Line Items]
Gross	655,182		655,182		662,611
Accumulated Amortization	(367,000)		(367,000)		(354,011)
Net	288,182		288,182		308,600
Impairment of intangible assets				$ 32,300
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Gross	26,752		26,752		26,409
Accumulated Amortization	(18,900)		(18,900)		(16,249)
Net	7,852		7,852		10,160
Tradenames and licenses
Finite-Lived Intangible Assets [Line Items]
Gross	127,311		127,311		127,176
Accumulated Amortization	(72,290)		(72,290)		(67,118)
Net	$ 55,021		$ 55,021		$ 60,058