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Debt and Lines of Credit - Additional Information (Details) - USD ($)	1 Months Ended						3 Months Ended		12 Months Ended
	May 31, 2020	Apr. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Aug. 31, 2019	May 31, 2018	Mar. 31, 2019	Jun. 30, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Commercial paper									$ 0
Debt repaid						$ 500,000,000
Proceeds from issuance of long-term debt									1,498,000,000	$ 1,491,000,000	$ 1,500,000,000
Interest and debt expense									190,000,000	170,000,000	125,000,000
Interest paid									$ 182,000,000	$ 156,000,000	$ 114,000,000
Notes due 2025 at 1.375%
Debt Instrument [Line Items]
Principal amount			$ 750,000,000
Payments of debt issuance costs			4,000,000
Proceeds from issuance of long-term debt			$ 749,000,000
Long-term debt stated interest rate (in percentage)									1.375%
Notes due 2020 at 1.75%
Debt Instrument [Line Items]
Debt repaid		$ 500,000,000
Long-term debt stated interest rate (in percentage)									1.75%
Notes due 2030 at 1.75%
Debt Instrument [Line Items]
Principal amount	$ 750,000,000
Payments of debt issuance costs	5,000,000
Proceeds from issuance of long-term debt	$ 749,000,000
Long-term debt stated interest rate (in percentage)									1.75%
Notes due 2039 at 3.875%
Debt Instrument [Line Items]
Principal amount							$ 750,000,000
Payments of debt issuance costs							7,000,000
Proceeds from issuance of long-term debt							$ 743,000,000
Long-term debt stated interest rate (in percentage)									3.875%
Notes due 2020 at 1.75%
Debt Instrument [Line Items]
Debt repaid					$ 750,000,000
Notes due 2029 at 2.25%
Debt Instrument [Line Items]
Principal amount				$ 750,000,000
Payments of debt issuance costs				5,000,000
Proceeds from issuance of long-term debt				$ 748,000,000
Long-term debt stated interest rate (in percentage)									2.25%
Notes due 2048 at 4.15%
Debt Instrument [Line Items]
Principal amount								$ 1,500,000,000
Payments of debt issuance costs								16,000,000
Proceeds from issuance of long-term debt								1,500,000,000
Long-term debt stated interest rate (in percentage)									4.15%
4.15% Notes issued in May 2018
Debt Instrument [Line Items]
Principal amount						$ 1,300,000,000
4.15% Notes issued in June 2018
Debt Instrument [Line Items]
Principal amount								$ 200,000,000
Revolving credit facility
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity									$ 2,000,000,000