Schedule I - Condensed Financial Information of Parent (Dividends from Subsidiaries and Affiliates) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Condensed Cash Flow Statements, Captions [Line Items]
Proceeds from Divestiture of Businesses and Interests in Affiliates	$ 169	$ 178	$ 2,020
SEC Schedule, 12-04, Cash Dividends Paid to Registrant, Consolidated Subsidiaries	1,000	1,000	1,900
SEC Schedule, 12-04, Cash Dividends Paid to Registrant, Consolidated Subsidiaries	1,000	1,000	$ 1,900
Parent Company [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Proceeds from Divestiture of Businesses and Interests in Affiliates	$ 302	$ 200