Income Tax (Total Income Taxes Provided) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Effects Allocated Directly to Equity [Abstract]
Income Tax Expense (Benefit)	$ 262	$ 130	$ (679)
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Tax	681	(368)	307
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax	3	19	(42)
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, Tax	(5)	0	0
Income Tax Expense (Benefit), Intraperiod Tax Allocation	$ 941	$ (219)	$ (414)