Borrowings - Interest on Debt (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Interest on Debt
Interest capitalized	$ 3	$ 5
Total interest paid and accrued	775	891
Cost of financing
Interest on Debt
Interest paid	210	237
Interest expense
Interest on Debt
Interest paid	$ 562	$ 649