Income Taxes Income Taxes - Effect of Income Taxes on Net Income and Stockholders' Equity (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Expense (Benefit) [Roll Forward]
Income tax expense (benefit)	$ 32	$ 5	$ 44
Net Unrealized Losses On Securities Tax Effect	14	12	(31)
Valuation Allowances And Reserves Charged To Equity	(23)	(9)	(5)
Income Tax Effects Allocated Directly to Equity	(8)	3	0
Unrealized Loss on FX Tax Effect	0	0	26
Other Comprehensive Income (Loss), Financial Liability, Fair Value Option, Reclassification Adjustment from AOCI for Derecognition, Tax			0
Income Tax Effects Allocated Directly to Equity, Other	$ 24	$ 8	$ 44