Long-Term Debt (Schedule Of Long-Term Debt) (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Dec. 31, 2019	Apr. 30, 2019	Mar. 31, 2019
Long-term debt [Line Items]
Less current portion	[1]	$ (100)	$ (70)
Total long-term debt		1,622	1,667
Fleet Agreement
Long-term debt [Line Items]
Vehicle finance leases	[2]	$ 94	95
Borrowing margin (as a percent)		2.45%
Variable rate basis		one-month LIBOR
Senior Secured Term Loan Facility Maturing In 2026 [Member] | Secured Debt [Member]
Long-term debt [Line Items]
Long-term debt	[3]	$ 592	593
Unamortized debt issuance costs		6	6
Unamortized original issue discount		1	1
5.125% Notes Maturing In 2024 [Member] | Notes [Member]
Long-term debt [Line Items]
Long-term debt	[4]	$ 742	$ 742
Interest rate (as a percent)		5.125%	5.125%
Unamortized debt issuance costs		$ 8	$ 8
7.45% notes maturing in 2027 | Notes [Member]
Long-term debt [Line Items]
Long-term debt	[5]	$ 167	$ 167
Interest rate (as a percent)		7.45%	7.45%	7.45%	7.45%
7.25% notes maturing in 2038 | Notes [Member]
Long-term debt [Line Items]
Long-term debt	[5]	$ 40	$ 40
Interest rate (as a percent)		7.25%	7.25%		7.25%
Notes 7.45%, And 7.25% Collectively [Member] | Notes [Member]
Long-term debt [Line Items]
Unamortized fair value adjustments related to purchase accounting		$ 27	$ 28
Other
Long-term debt [Line Items]
Long-term debt	[6]	86	100
Copesan Services, Inc. (“Copesan”) [Member] | Other
Long-term debt [Line Items]
Long-term debt		$ 86	$ 91

[1] The increase in the current portion of long-term debt consists of deferred purchase price and earnout payments on acquisitions due within 12 months.

[2] We have entered into a fleet management services agreement (the “Fleet Agreement”) which, among other things, allows us to obtain fleet vehicles through a leasing program. All leases under the Fleet Agreement are finance leases for accounting purposes. The lease rental payments include an interest component calculated using a variable rate based on one-month LIBOR plus other contractual adjustments and a borrowing margin totaling 2.45 percent.

[3] As of March 31, 2020 and December 31, 2019, presented net of $6 million in unamortized debt issuance costs in each period and $1 million of unamortized original issue discount in each period.

[4] As of March 31, 2020 and December 31, 2019, presented net of $8 million in unamortized debt issuance costs in each period.

[5] As of March 31, 2020 and December 31, 2019, collectively presented net of $27 million and $28 million, respectively, of unamortized fair value adjustments related to purchase accounting, which increases the effective interest rate from the coupon rates shown above.

[6] As of March 31, 2020 and December 31, 2019, includes approximately $86 million and $91 million, respectively, of future payments in connection with acquisitions.