Schedule I - Condensed Financial Information of Parent (Dividends from Subsidiaries and Affiliates) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Condensed Cash Flow Statements, Captions [Line Items]
Proceeds from Divestiture of Businesses and Interests in Affiliates	$ 2,020	$ 108	$ 538
SEC Schedule, 12-04, Cash Dividends Paid to Registrant, Consolidated Subsidiaries	1,900	$ 1,200	$ 1,000
Parent Company [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Proceeds from Divestiture of Businesses and Interests in Affiliates	$ 1,200