Parent Company (Interest Paid and Income Tax Refunds) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Condensed Financial Statements, Captions [Line Items]
Interest paid	$ 2,835	$ 1,743	$ 1,317
Income Tax Refunds/(Payments)	468	24	111
Parent Company
Condensed Financial Statements, Captions [Line Items]
Interest paid	288	287	317
Income Tax Refunds/(Payments)	$ 88	$ 40	$ 183