Organization, Basis of Presentation and Summary of Significant Accounting Policies (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Gain (loss) on interest rate fair value hedge ineffectiveness	$ (3,000,000)	$ (19,000,000)	$ (14,000,000)
Cash Equivalents [Abstract]
Overnight cash, Federal Reserve	322,000,000	1,800,000,000
Investments, Debt and Equity Securities [Abstract]
OTTI recognized for the period	0	0	0
Goodwill and Intangible Assets Disclosure [Abstract]
Impairment of goodwill	0	0	$ 0
Equity Method, Cost Method and Other Investments [Abstract]
Federal Home Loan Bank Stock	$ 20,000,000	$ 20,000,000
Software Development [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	4 years