Fair Value Disclosures (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Assets
Available-for-sale securities, debt securities	$ 1,660	$ 1,365
Recurring basis
Assets
Available-for-sale securities, debt securities	1,660	1,365
Equity Securities, FV-NI	344	346
Derivative Assets (Liabilities), at Fair Value, Net	82	45
Total Assets	2,086	1,756
U.S. treasury bonds
Assets
Available-for-sale securities, debt securities	16	9
U.S. treasury bonds | Recurring basis
Assets
Available-for-sale securities, debt securities	16	9
Other U.S. and non-U.S. government bonds
Assets
Available-for-sale securities, debt securities	51	54
Other U.S. and non-U.S. government bonds | Recurring basis
Assets
Available-for-sale securities, debt securities	51	54
Corporate bonds
Assets
Available-for-sale securities, debt securities	1,001	856
Corporate bonds | Recurring basis
Assets
Available-for-sale securities, debt securities	1,001	856
Asset-backed securities
Assets
Available-for-sale securities, debt securities	158	62
Asset-backed securities | Recurring basis
Assets
Available-for-sale securities, debt securities	158	62
U.S. governmental agency | Recurring basis
Assets
Available-for-sale securities, debt securities	364	331
Residential
Assets
Available-for-sale securities, debt securities	5	6
Residential | Recurring basis
Assets
Available-for-sale securities, debt securities	5	6
Commercial
Assets
Available-for-sale securities, debt securities	65	47
Commercial | Recurring basis
Assets
Available-for-sale securities, debt securities	65	47
Large capitalization value | Recurring basis
Assets
Equity Securities, FV-NI	173	187
Smaller company growth | Recurring basis
Assets
Equity Securities, FV-NI	32	33
REIT | Recurring basis
Assets
Equity Securities, FV-NI	139	126
Level 1 | Recurring basis
Assets
Available-for-sale securities, debt securities	16	9
Equity Securities, FV-NI	205	216
Total Assets	221	225
Level 1 | U.S. treasury bonds | Recurring basis
Assets
Available-for-sale securities, debt securities	16	9
Level 1 | Large capitalization value | Recurring basis
Assets
Equity Securities, FV-NI	173	187
Level 1 | Smaller company growth | Recurring basis
Assets
Equity Securities, FV-NI	32	29
Level 2 | Recurring basis
Assets
Available-for-sale securities, debt securities	1,644	1,356
Derivative Assets (Liabilities), at Fair Value, Net	82	45
Total Assets	1,726	1,401
Level 2 | Other U.S. and non-U.S. government bonds | Recurring basis
Assets
Available-for-sale securities, debt securities	51	54
Level 2 | Corporate bonds | Recurring basis
Assets
Available-for-sale securities, debt securities	1,001	856
Level 2 | Asset-backed securities | Recurring basis
Assets
Available-for-sale securities, debt securities	158	62
Level 2 | U.S. governmental agency | Recurring basis
Assets
Available-for-sale securities, debt securities	364	331
Level 2 | Residential | Recurring basis
Assets
Available-for-sale securities, debt securities	5	6
Level 2 | Commercial | Recurring basis
Assets
Available-for-sale securities, debt securities	65	47
Level 3 | Recurring basis
Assets
Equity Securities, FV-NI		4
Total Assets		4
Level 3 | Smaller company growth | Recurring basis
Assets
Equity Securities, FV-NI		4
Fair Value Measured on Net Asset Value (NAV) | Recurring basis
Assets
Equity Securities, FV-NI	139	126
Total Assets	139	126
Fair Value Measured on Net Asset Value (NAV) | REIT | Recurring basis
Assets
Equity Securities, FV-NI	139	126
Financial Products | Level 3 | Nonrecurring basis
Assets and liabilities measured on a recurring basis at fair value
Fair value of impaired loans	$ 269	$ 343