Revenue Recognition (Schedule Of Disaggregated Revenue) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Subtotal	$ 1,368,489	$ 1,319,851	$ 1,223,524
Net revenue	1,334,667	1,281,184	1,197,562
Roto-Rooter [Member]
Subtotal	762,035	675,091	603,838
Implicit price concessions and credit memos	(17,119)	(17,720)	(18,752)
Net revenue	744,916	657,371	585,086
Roto-Rooter [Member] | Short-Term Core Service Jobs [Member]
Subtotal	552,500	482,625	425,845
Roto-Rooter [Member] | Water Restoration [Member]
Subtotal	126,378	115,949	109,484
Roto-Rooter [Member] | Contractor Revenue [Member]
Subtotal	64,727	58,086	50,169
Roto-Rooter [Member] | Franchise Fees [Member]
Subtotal	4,893	6,152	6,382
Roto-Rooter [Member] | All Other [Member]
Subtotal	$ 13,537	$ 12,279	$ 11,958