Summary of Significant Accounting Policies Summary of Significant Accounting Policies (Intangible Assets) (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Acquired Finite-Lived Intangible Assets [Line Items]
Accumulated Amortization Of Values Of Business Acquired Distribution Agreements And Customer Relationships	$ 96	$ 88
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	7
Finite-Lived Intangible Assets, Amortization Expense, Year Two	6
Finite-Lived Intangible Assets, Amortization Expense, Year Three	6
Finite-Lived Intangible Assets, Amortization Expense, Year Four	6
Present Value of Future Insurance Profits, Net	4	5
Other Intangible Assets [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived Intangible Assets Acquired	30	34
Accumulated Amortization Of Values Of Business Acquired Distribution Agreements And Customer Relationships	12	8
Amortization of Intangible Assets	4	$ 4	$ 4
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	4
Finite-Lived Intangible Assets, Amortization Expense, Year Two	4
Finite-Lived Intangible Assets, Amortization Expense, Year Three	4
Finite-Lived Intangible Assets, Amortization Expense, Year Four	4
Finite-Lived Intangible Assets, Amortization Expense, Year Five	$ 4