Financing Agreements - Additional Information (Details) - USD ($)													3 Months Ended		12 Months Ended
		Sep. 30, 2020	Dec. 31, 2019		Nov. 30, 2019	Nov. 26, 2019	Nov. 22, 2019	Aug. 30, 2019	Feb. 28, 2019	Sep. 18, 2017	Sep. 14, 2017	Apr. 04, 2017	Dec. 31, 2019		Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017
Debt Instrument [Line Items]
Loss on extinguishment of debt												$ 6,000,000	$ 9,000,000		$ 9,000,000				$ 19,000,000
Write-off of deferred financing costs															2,000,000				4,000,000
Redemption premium															$ 7,000,000				$ 15,000,000
Term A Facility [Member]
Debt Instrument [Line Items]
Net proceeds of the offering									$ 225,000,000		$ 275,000,000
Current aggregate facility									500,000,000
Line of Credit Facility, Periodic Payment									8,000,000
Line of Credit Facility, Interest Rate at Period End			3.30%										3.30%		3.30%
Term Facility [Member]
Debt Instrument [Line Items]
Financing costs								$ 13,000,000
Term B Facility [Member]
Debt Instrument [Line Items]
Net proceeds of the offering									450,000,000
Current aggregate facility									$ 450,000,000
Line Of Credit Facility, Periodic Payment, Principal, Percentage									0.25%
Line of Credit Facility, Interest Rate at Period End			4.05%										4.05%		4.05%
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Net proceeds of the offering								100,000,000
Financing costs								4,000,000
Current aggregate facility								$ 1,000,000,000	$ 750,000,000
Fronting fee rate															0.125%
Line of credit facility, amount outstanding			$ 0										$ 0		$ 0
Utilized for letters of credit			21,000,000										21,000,000		21,000,000
Available borrowing capacity			979,000,000										979,000,000		979,000,000
Revolving Credit Facility [Member] | Maximum [Member]
Debt Instrument [Line Items]
Line of credit facility applied to letters of credit			$ 275,000,000										$ 275,000,000		$ 275,000,000
Senior Notes Due November 2027 [Member]
Debt Instrument [Line Items]
Senior notes issued					$ 300,000,000
Interest rate			5.375%		5.375%								5.375%		5.375%
Net proceeds of the offering					$ 296,000,000
Financing costs					4,000,000
Senior Notes Due November 2027 [Member] | Debt Instrument, Redemption, Period One [Member]
Debt Instrument [Line Items]
Debt redemption price			105.375%
Senior Notes Due November 2027 [Member] | Debt Instrument, Redemption, Period One [Member] | Minimum [Member]
Debt Instrument [Line Items]
Percent of original principal amount that must remain outstanding after the redemption			50.00%
Senior Notes Due November 2027 [Member] | Debt Instrument, Redemption, Period One [Member] | Maximum [Member]
Debt Instrument [Line Items]
Percent of notes redeemable			35.00%
Senior Notes Due November 2027 [Member] | Debt Instrument, Redemption, Period Two [Member]
Debt Instrument [Line Items]
Debt redemption price			100.00%
Senior Notes Due September 2023 [Member]
Debt Instrument [Line Items]
Interest rate			6.00%										6.00%		6.00%		6.00%
Senior notes redeemed						$ 138,000,000	$ 162,000,000
Debt redemption price						102.00%	102.25%
Loss on extinguishment of debt					9,000,000
Write-off of deferred financing costs					$ 2,000,000
Senior Notes Due April 2025 [Member]
Debt Instrument [Line Items]
Senior notes issued												$ 400,000,000
Interest rate			5.75%	[1]								5.75%	5.75%	[1]	5.75%	[1]	5.75%	[1]
Net proceeds of the offering												$ 394,000,000
Financing costs												6,000,000
Senior Notes Due April 2025 [Member] | Debt Instrument, Redemption, Period One [Member]
Debt Instrument [Line Items]
Debt redemption price			105.75%
Senior Notes Due April 2025 [Member] | Debt Instrument, Redemption, Period One [Member] | Minimum [Member]
Debt Instrument [Line Items]
Percent of original principal amount that must remain outstanding after the redemption			50.00%
Senior Notes Due April 2025 [Member] | Debt Instrument, Redemption, Period One [Member] | Maximum [Member]
Debt Instrument [Line Items]
Percent of notes redeemable			35.00%
Senior Notes Due April 2025 [Member] | Debt Instrument, Redemption, Period Two [Member]
Debt Instrument [Line Items]
Debt redemption price			100.00%
Senior Notes Due September 2021 [Member]
Debt Instrument [Line Items]
Senior notes redeemed										$ 350,000,000		$ 100,000,000
Debt redemption price										102.688%		104.031%
Loss on extinguishment of debt										$ 13,000,000
Write-off of deferred financing costs										3,000,000		$ 1,000,000
Redemption premium										$ 10,000,000		4,000,000
Other Indebtedness [Member]
Debt Instrument [Line Items]
Redemption premium												$ 1,000,000
Senior Notes Due June 2026 [Member]
Debt Instrument [Line Items]
Interest rate	[1]		6.50%										6.50%		6.50%		6.50%
Senior Notes Due June 2026 [Member] | Debt Instrument, Redemption, Period One [Member]
Debt Instrument [Line Items]
Debt redemption price			100.00%
Senior Notes Due June 2026 [Member] | Debt Instrument, Redemption, Period Two [Member]
Debt Instrument [Line Items]
Debt redemption price			103.25%
Cash Flow Hedging [Member] | Senior Notes Due April 2025 [Member]
Debt Instrument [Line Items]
Interest rate			5.75%										5.75%		5.75%
Derivative, Fixed Interest Rate			3.85%										3.85%		3.85%
Cash Flow Hedging [Member] | Senior Notes Due June 2026 [Member]
Debt Instrument [Line Items]
Interest rate			6.50%										6.50%		6.50%
Derivative, Fixed Interest Rate			5.14%										5.14%		5.14%
Currency Swap [Member] | Cash Flow Hedging [Member] | Senior Notes Due April 2025 [Member]
Debt Instrument [Line Items]
Derivative, Fixed Interest Rate												3.85%
Forecast [Member] | Term A Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Periodic Payment		$ 7,000,000
Base Rate [Member] | Term B Facility [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate															1.25%
Eurodollar [Member] | Term B Facility [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate															2.25%

[1] * In conjunction with the issuance of the April 2025 Notes we entered into 8-year fixed-to-fixed cross-currency swaps which have the effect of economically converting the April 2025 Notes to euro-denominated debt at a fixed rate of 3.850%. In conjunction with the issuance of the June 2026 Notes we entered into 10-year fixed-to-fixed cross-currency swaps which have the effect of economically converting the June 2026 Notes to euro-denominated debt at a fixed rate of 5.140%. See Note 16 for additional information.