Face (par) amount of debt instrument at time of issuance.

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Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

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Incremental percentage increase (decrease) in the stated rate on a debt instrument.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Percentage of principal amount of debt redeemed.

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Fair value amount of debt instrument that was repurchased.

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Amount of unused borrowing capacity under the long-term financing arrangement that is available to the entity as of the balance sheet date.

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Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

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The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

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The cash inflow from additional borrowings, net of cash paid to third parties in connection with debt origination.

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Describes the term of the registration payment arrangement.

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Debt - Debt (Details) £ in Millions, $ in Millions	1 Months Ended	3 Months Ended		9 Months Ended
Debt - Debt (Details) £ in Millions, $ in Millions	Jun. 17, 2019	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 AUD ($)	Sep. 30, 2019 GBP (£)	Aug. 19, 2019 USD ($)	May 23, 2019 USD ($)	Jan. 15, 2019 USD ($)
Debt Instruments [Line Items]
Registration Payment Arrangement, Term	three
Proceeds from Debt, Net of Issuance Costs				$ 1,380,000,000
Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed				100.00%
Loss on extinguishment of debt		$ 90,000,000	$ 0	$ 90,000,000	$ 6,000,000
Club Facility [Member]
Debt Instruments [Line Items]
Letters of Credit Outstanding, Amount		165,000,000		165,000,000			£ 60
Bilateral Facility [Member]
Debt Instruments [Line Items]
Letters of Credit Outstanding, Amount		8,000,000		8,000,000
Debt Instrument, Unused Borrowing Capacity, Amount		17,000,000		$ 17,000,000
Australian Dollar Facility [Member] [Member]
Debt Instruments [Line Items]
Letters of Credit Outstanding, Amount						$ 24
Debt Instrument, Unused Borrowing Capacity, Amount						$ 26
Senior Note Two Point Eight due in Two Thousand Twenty Nine [Member]
Debt Instruments [Line Items]
Debt Instrument, Interest Rate, Increase (Decrease)				2000.00%
Senior Note Three Point Six due in Two Thousand Forty Nine [Member]
Debt Instruments [Line Items]
Debt Instrument, Interest Rate, Increase (Decrease)				2500.00%
Senior Notes \| Senior Note Six Point Zero Percent Due in Two Thousand Nineteen [Member]
Debt Instruments [Line Items]
Repayment of debt										$ 413,000,000
Interest rate										6.00%
Senior Notes \| Senior Note Five Point Seven Five Percent Due in Two Thousand Twenty Three [Member]
Debt Instruments [Line Items]
Interest rate									5.75%
Senior Notes									$ 265,000,000
Debt Instrument, Fair Value Disclosure									$ 284,000,000
Senior Notes \| Senior Note Two Point Eight due in Two Thousand Twenty Nine [Member]
Debt Instruments [Line Items]
Interest rate								2.80%
Senior Notes								$ 600,000,000
Senior Notes \| Senior Note Three Point Six due in Two Thousand Forty Nine [Member]
Debt Instruments [Line Items]
Interest rate								3.60%
Senior Notes								$ 800,000,000
Senior Notes \| Senior Note Five Point Seven Five due in Two Thousand Twenty Three [Member]
Debt Instruments [Line Items]
Repayment of debt		$ 265		$ 265
Interest rate		5.75%		5.75%		5.75%	5.75%
Senior Notes \| Senior Note Five Point One Twenty Five due in Two Thousand Twenty Two [Member]
Debt Instruments [Line Items]
Repayment of debt		$ 800		$ 800
Interest rate		5.125%		5.125%		5.125%	5.125%