Notes Payable - General (Details) - Notes and bonds payable		1 Months Ended
	Nov. 30, 2021 USD ($)	Dec. 31, 2021 USD ($)	Nov. 30, 2021 USD ($)	Jan. 31, 2021 USD ($)	Dec. 31, 2021 GBP (£)	Nov. 01, 2021 USD ($)	Jul. 31, 2021 GBP (£)	Dec. 31, 2020 USD ($)	Oct. 31, 2020 GBP (£)	Jul. 31, 2020 USD ($)	May 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Jun. 30, 2019 USD ($)	May 31, 2019 GBP (£)
Debt
Total principal amount		$ 12,257,000,000						$ 8,303,000,000
Unamortized net premiums and deferred financing costs		243,000,000						(35,000,000)
Net payable amount		12,500,000,000						$ 8,268,000,000
3.250% notes, $450 issued in October 2012 and $500 issued in December 2017, both due in October 2022 (1)
Debt
Interest rate (as a percent)				3.25%				3.25%
Principal amount								$ 950,000,000
Total principal amount		$ 0						950,000,000
Early redemption of notes				$ 950,000,000
3.250% notes, issued in October 2012 and due in October 2022
Debt
Principal amount								450,000,000
3.250% notes, issued in December 2017 and due in October 2022
Debt
Principal amount								$ 500,000,000
4.650% notes, issued in July 2013 and due in August 2023 (2)
Debt
Interest rate (as a percent)		4.65%			4.65%			4.65%
Principal amount								$ 750,000,000
Total principal amount		$ 0						750,000,000
Early redemption of notes		$ 750,000,000.0
4.600% notes, $500 issued February 2014, of which $485 was exchanged in November 2021, both due in February 2024 (3)
Debt
Interest rate (as a percent)	4.60%	4.60%	4.60%		4.60%
Principal amount		$ 500,000,000
Amount exchanged	$ 485,000,000		$ 485,000,000
Total principal amount		$ 500,000,000						0
3.875% notes, issued in June 2014 and due in July 2024
Debt
Interest rate (as a percent)		3.875%			3.875%
Principal amount		$ 350,000,000
Total principal amount		$ 350,000,000						350,000,000
3.875% notes, issued in April 2018 and due in April 2025
Debt
Interest rate (as a percent)		3.875%			3.875%
Principal amount		$ 500,000,000
Total principal amount		$ 500,000,000						500,000,000
4.625% notes, $550 issued October 2018, of which $544 was exchanged in November 2021, both due in November 2025 (3)
Debt
Interest rate (as a percent)	4.625%	4.625%	4.625%		4.625%
Principal amount		$ 550,000,000
Amount exchanged	$ 544,000,000		$ 544,000,000
Total principal amount		$ 550,000,000						$ 0
0.750% notes, issued December 2020 and due in March 2026
Debt
Interest rate (as a percent)		0.75%			0.75%			0.75%
Principal amount		$ 325,000,000						$ 325,000,000
Total principal amount		$ 325,000,000						325,000,000
4.875% notes, $600 issued June 2016, of which $596 was exchanged in November 2021, both due in June 2026 (3)
Debt
Interest rate (as a percent)	4.875%	4.875%	4.875%		4.875%
Principal amount		$ 600,000,000
Amount exchanged	$ 596,000,000		$ 596,000,000
Total principal amount		$ 600,000,000						0
4.125% notes, $250 issued in September 2014 and $400 issued in March 2017, both due in October 2026
Debt
Interest rate (as a percent)		4.125%			4.125%
Principal amount		$ 650,000,000
Total principal amount		650,000,000						650,000,000
4.125% notes, issued in September 2014 and due in October 2026
Debt
Principal amount		250,000,000
4.125% notes, issued in March 2017 and due in October 2026
Debt
Principal amount		$ 400,000,000
3.000% notes, issued in October 2016 and due in January 2027
Debt
Interest rate (as a percent)		3.00%			3.00%
Principal amount		$ 600,000,000
Total principal amount		$ 600,000,000						600,000,000
1.125% notes, issued in July 2021 and due in July 2027
Debt
Interest rate (as a percent)		1.125%			1.125%		1.125%
Principal amount | £					£ 400,000,000		£ 400,000,000
Total principal amount		$ 541,000,000						0
3.950% notes, $600 issued August 2017, of which $594 was exchanged in November 2021, both due in August 2027 (3)
Debt
Interest rate (as a percent)	3.95%	3.95%	3.95%		3.95%
Principal amount		$ 600,000,000
Amount exchanged	$ 594,000,000		$ 594,000,000
Total principal amount		$ 600,000,000						0
3.650% notes, issued in December 2017 and due in January 2028
Debt
Interest rate (as a percent)		3.65%			3.65%
Principal amount		$ 550,000,000
Total principal amount		$ 550,000,000						550,000,000
3.400% notes, $600 issued June 2020, of which $598 was exchanged in November 2021, both due in January 2028 (3)
Debt
Interest rate (as a percent)	3.40%	3.40%	3.40%		3.40%
Principal amount		$ 600,000,000
Amount exchanged	$ 598,000,000		$ 598,000,000
Total principal amount		$ 600,000,000						0
2.200% notes, $500 issued November 2020, of which $497 was exchanged in November 2021, both due in June 2028 (3)
Debt
Interest rate (as a percent)	2.20%	2.20%	2.20%		2.20%
Principal amount		$ 500,000,000
Amount exchanged	$ 497,000,000		$ 497,000,000
Total principal amount		$ 500,000,000						0
3.250% notes, issued in June 2019 and due in June 2029
Debt
Interest rate (as a percent)		3.25%			3.25%								3.25%
Principal amount		$ 500,000,000											$ 500,000,000
Total principal amount		$ 500,000,000						500,000,000
3.100% notes, $600 issued December 2019, of which $596 was exchanged in November 2021, both due in December 2029 (3) (4)
Debt
Interest rate (as a percent)	3.10%	3.10%	3.10%		3.10%
Principal amount		$ 599,000,000				$ 599,000,000						$ 600,000,000
Amount exchanged	$ 596,000,000		$ 596,000,000
Total principal amount		$ 599,000,000						0
Early participation premium per $1000 of principal						$ 30
1.625% notes, issued in October 2020 and due December 2030
Debt
Interest rate (as a percent)		1.625%			1.625%				1.625%
Principal amount | £					£ 400,000,000				£ 400,000,000
Total principal amount		$ 541,000,000						547,000,000
3.250% notes, $600 issued in May 2020 and $350 issued in July 2020, both due in January 2031
Debt
Interest rate (as a percent)		3.25%			3.25%
Principal amount		$ 950,000,000
Total principal amount		950,000,000						950,000,000
3.250% notes, issued in May 2020 and due in January 2031
Debt
Interest rate (as a percent)											3.25%
Principal amount		600,000,000									$ 600,000,000
3.250% notes, issued in July 2020 and due in January 2031
Debt
Interest rate (as a percent)										3.25%
Principal amount		$ 350,000,000								$ 350,000,000
2.850% notes, $700 issued November 2020, of which $699 was exchanged in November 2021, both due in December 2032 (3)
Debt
Interest rate (as a percent)	2.85%	2.85%	2.85%		2.85%
Principal amount		$ 700,000,000
Amount exchanged	$ 699,000,000		$ 699,000,000
Total principal amount		$ 700,000,000						$ 0
1.800% notes, issued in December 2020 and due in March 2033
Debt
Interest rate (as a percent)		1.80%			1.80%			1.80%
Principal amount		$ 400,000,000						$ 400,000,000
Total principal amount		$ 400,000,000						400,000,000
1.750% notes, issued in July 2021 and due in July 2033
Debt
Interest rate (as a percent)		1.75%			1.75%		1.75%
Principal amount | £					£ 350,000,000		£ 350,000,000
Total principal amount		$ 474,000,000						0
2.730% notes, issued in May 2019 and due in May 2034
Debt
Interest rate (as a percent)		2.73%			2.73%									2.73%
Principal amount | £					£ 315,000,000									£ 315,000,000
Total principal amount		$ 427,000,000						431,000,000
5.875% bonds, $100 issued in March 2005 and $150 issued in June 2011, both due in March 2035
Debt
Interest rate (as a percent)		5.875%			5.875%
Principal amount		$ 250,000,000
Total principal amount		250,000,000						250,000,000
5.875% bonds, issued in March 2005 and due in March 2035
Debt
Principal amount		100,000,000
5.875% bonds, issued in June 2011 and due in March 2035
Debt
Principal amount		$ 150,000,000
4.650% notes, $300 issued in March 2017 and $250 issued in December 2017, both due in March 2047
Debt
Interest rate (as a percent)		4.65%			4.65%
Principal amount		$ 550,000,000
Total principal amount		550,000,000						$ 550,000,000
4.650% notes, issued in March 2017 and due in March 2047
Debt
Principal amount		300,000,000
4.650% notes, issued in December 2017 and due in March 2047
Debt
Principal amount		$ 250,000,000