Debt Obligations (Changes in Debt Obligations) (Details) - USD ($)	1 Months Ended			9 Months Ended
	Apr. 30, 2020	Mar. 31, 2020	Feb. 29, 2020	Sep. 30, 2020	Jun. 30, 2020	Apr. 30, 2019	Jun. 30, 2016	May 31, 2016	May 31, 2014
Changes in Long-Term Debt Obligations [Roll Forward]
Total long-term debt at beginning of period				$ 2,996,000,000
Additions				1,928,000,000
Payments, Foreign Currency Translation and Accretion				(1,353,000,000)
Total long-term debt at end of period				3,571,000,000
Changes In Debt Obligations [Roll Forward]
Total debt obligations at beginning of period				3,387,000,000
Additions				2,918,000,000
Payments, Foreign Currency Translation and Accretion				(2,734,000,000)
Total debt obligations at end of period				$ 3,571,000,000
3.875% senior unsecured notes repaid on March 16, 2020
Schedule of Debt [Line Items]
Stated rate				3.875%
4.25% senior unsecured notes due June 1, 2024
Schedule of Debt [Line Items]
Stated rate				4.25%
1.75% senior unsecured notes due May 19, 2023
Schedule of Debt [Line Items]
Stated rate				1.75%
3.85% senior unsecured notes due June 30, 2026
Schedule of Debt [Line Items]
Stated rate				3.85%
1.75% senior unsecured notes due March 28, 2029
Schedule of Debt [Line Items]
Stated rate				1.75%
0.875% senior unsecured notes due February 13, 2030
Schedule of Debt [Line Items]
Stated rate				0.875%
3.25% senior unsecured notes due April 28, 2050
Schedule of Debt [Line Items]
Stated rate				3.25%
Senior Notes | 3.875% senior unsecured notes repaid on March 16, 2020
Schedule of Debt [Line Items]
Stated rate				3.875%
Changes in Long-Term Debt Obligations [Roll Forward]
Long-term debt obligations at beginning of period				$ 671,000,000
Additions				0
Payments, Foreign Currency Translation and Accretion				(671,000,000)
Long-term debt obligations at end of period				0
Senior Notes | 4.25% senior unsecured notes due June 1, 2024
Schedule of Debt [Line Items]
Stated rate									4.25%
Changes in Long-Term Debt Obligations [Roll Forward]
Long-term debt obligations at beginning of period				497,000,000
Additions				0
Payments, Foreign Currency Translation and Accretion				1,000,000
Long-term debt obligations at end of period				498,000,000
Senior Notes | 1.75% senior unsecured notes due May 19, 2023
Schedule of Debt [Line Items]
Stated rate								1.75%
Changes in Long-Term Debt Obligations [Roll Forward]
Long-term debt obligations at beginning of period				668,000,000
Additions				0
Payments, Foreign Currency Translation and Accretion				32,000,000
Long-term debt obligations at end of period				700,000,000
Senior Notes | 3.85% senior unsecured notes due June 30, 2026
Schedule of Debt [Line Items]
Stated rate							3.85%
Changes in Long-Term Debt Obligations [Roll Forward]
Long-term debt obligations at beginning of period				497,000,000
Additions				0
Payments, Foreign Currency Translation and Accretion				0
Long-term debt obligations at end of period				497,000,000
Senior Notes | 1.75% senior unsecured notes due March 28, 2029
Schedule of Debt [Line Items]
Stated rate						1.75%
Changes in Long-Term Debt Obligations [Roll Forward]
Long-term debt obligations at beginning of period				665,000,000
Additions				0
Payments, Foreign Currency Translation and Accretion				32,000,000
Long-term debt obligations at end of period				697,000,000
Senior Notes | 0.875% senior unsecured notes due February 13, 2030
Changes in Long-Term Debt Obligations [Roll Forward]
Long-term debt obligations at beginning of period				0
Additions			$ 644,000,000	644,000,000
Payments, Foreign Currency Translation and Accretion				52,000,000
Long-term debt obligations at end of period				696,000,000
Senior Notes | 3.25% senior unsecured notes due April 28, 2050
Schedule of Debt [Line Items]
Stated rate					3.25%
Changes in Long-Term Debt Obligations [Roll Forward]
Long-term debt obligations at beginning of period				0
Additions	$ 485,000,000			485,000,000
Payments, Foreign Currency Translation and Accretion				0
Long-term debt obligations at end of period				485,000,000
$1 billion senior unsecured revolving credit facility due April 25, 2022
Schedule of Debt [Line Items]
Facility borrowing capacity				$ 1,000,000,000
Average interest rate				2.37%
Changes in Long-Term Debt Obligations [Roll Forward]
Long-term debt obligations at beginning of period				$ (2,000,000)
Additions		$ 799,000,000		799,000,000
Payments, Foreign Currency Translation and Accretion				(799,000,000)
Long-term debt obligations at end of period				(2,000,000)
Short-term debt - commercial paper
Changes In Short-Term Debt Obligations [Roll Forward]
Short-term debt - commercial paper beginning balance				391,000,000
Additions				990,000,000
Payments, Foreign Currency Translation and Accretion				(1,381,000,000)
Short-term debt - commercial paper ending balance				$ 0