Debt (Tables)

3 Months Ended

Mar. 31, 2021

Debt Disclosure [Abstract]

Summary of debt

A summary of our outstanding unsecured senior notes is as follows (amounts in millions):

				At March 31, 2021			At December 31, 2020
Unsecured Senior Notes	Interest Rate	Semi-Annual Interest Payments Due On	Maturity	Principal		Fair Value (Level 2)	Principal		Fair Value (Level 2)
2026 Notes	3.40%	Mar. 15 & Sept. 15	Sept. 2026	850		930	850		970
2027 Notes	3.40%	Jun. 15 & Dec. 15	Jun. 2027	400		438	400		454
2030 Notes	1.35%	Mar. 15 & Sept. 15	Sept. 2030	500		450	500		490
2047 Notes	4.50%	Jun. 15 & Dec. 15	Jun. 2047	400		469	400		525
2050 Notes	2.50%	Mar. 15 & Sept. 15	Sept. 2050	1,500		1,258	1,500		1,462
Total gross long-term debt				$	3,650		$	3,650
Unamortized discount and deferred financing costs				(44)			(45)
Total net carrying amount				$	3,606		$	3,605