Fair Value Disclosures (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Assets
Total Debt Securities	$ 1,328	$ 1,151
Recurring basis
Assets
Total Debt Securities	1,328	1,151
Equity securities	489	425
Derivative Assets (Liabilities), at Fair Value, Net	(55)
Total Assets	1,872	1,576
Liabilities
Derivative Liabilities, at Fair Value, Net		19
Total Liabilities		19
U.S. treasury bonds
Assets
Total Debt Securities	9	9
U.S. treasury bonds | Recurring basis
Assets
Total Debt Securities	9	9
Other U.S. and non-U.S. government bonds
Assets
Total Debt Securities	48	42
Other U.S. and non-U.S. government bonds | Recurring basis
Assets
Total Debt Securities	48	42
Corporate bonds
Assets
Total Debt Securities	840	720
Corporate bonds | Recurring basis
Assets
Total Debt Securities	840	720
Asset-backed securities
Assets
Total Debt Securities	53	63
Asset-backed securities | Recurring basis
Assets
Total Debt Securities	53	63
U.S. governmental agency | Recurring basis
Assets
Total Debt Securities	331	297
Residential
Assets
Total Debt Securities	6	7
Residential | Recurring basis
Assets
Total Debt Securities	6	7
Commercial
Assets
Total Debt Securities	41	13
Commercial | Recurring basis
Assets
Total Debt Securities	41	13
Large capitalization value | Recurring basis
Assets
Equity securities	310	260
Smaller company growth | Recurring basis
Assets
Equity securities	55	46
REIT | Recurring basis
Assets
Equity securities	124	119
Level 1 | Recurring basis
Assets
Total Debt Securities	9	9
Equity securities	357	306
Derivative Assets (Liabilities), at Fair Value, Net	0
Total Assets	366	315
Liabilities
Derivative Liabilities, at Fair Value, Net		0
Total Liabilities		0
Level 1 | U.S. treasury bonds | Recurring basis
Assets
Total Debt Securities	9	9
Level 1 | Other U.S. and non-U.S. government bonds | Recurring basis
Assets
Total Debt Securities	0	0
Level 1 | Corporate bonds | Recurring basis
Assets
Total Debt Securities	0	0
Level 1 | Asset-backed securities | Recurring basis
Assets
Total Debt Securities	0	0
Level 1 | U.S. governmental agency | Recurring basis
Assets
Total Debt Securities	0	0
Level 1 | Residential | Recurring basis
Assets
Total Debt Securities	0	0
Level 1 | Commercial | Recurring basis
Assets
Total Debt Securities	0	0
Level 1 | Large capitalization value | Recurring basis
Assets
Equity securities	310	260
Level 1 | Smaller company growth | Recurring basis
Assets
Equity securities	47	46
Level 1 | REIT | Recurring basis
Assets
Equity securities	0	0
Level 2 | Recurring basis
Assets
Total Debt Securities	1,319	1,142
Equity securities	0	0
Derivative Assets (Liabilities), at Fair Value, Net	(55)	19
Total Assets	1,374	1,142
Liabilities
Total Liabilities		19
Level 2 | U.S. treasury bonds | Recurring basis
Assets
Total Debt Securities	0	0
Level 2 | Other U.S. and non-U.S. government bonds | Recurring basis
Assets
Total Debt Securities	48	42
Level 2 | Corporate bonds | Recurring basis
Assets
Total Debt Securities	840	720
Level 2 | Asset-backed securities | Recurring basis
Assets
Total Debt Securities	53	63
Level 2 | U.S. governmental agency | Recurring basis
Assets
Total Debt Securities	331	297
Level 2 | Residential | Recurring basis
Assets
Total Debt Securities	6	7
Level 2 | Commercial | Recurring basis
Assets
Total Debt Securities	41	13
Level 2 | Large capitalization value | Recurring basis
Assets
Equity securities	0	0
Level 2 | Smaller company growth | Recurring basis
Assets
Equity securities	0	0
Level 2 | REIT | Recurring basis
Assets
Equity securities	0	0
Level 3 | Recurring basis
Assets
Total Debt Securities	0	0
Equity securities	8	0
Derivative Assets (Liabilities), at Fair Value, Net	0
Total Assets	8	0
Liabilities
Derivative Liabilities, at Fair Value, Net		0
Total Liabilities		0
Level 3 | U.S. treasury bonds | Recurring basis
Assets
Total Debt Securities	0	0
Level 3 | Other U.S. and non-U.S. government bonds | Recurring basis
Assets
Total Debt Securities	0	0
Level 3 | Corporate bonds | Recurring basis
Assets
Total Debt Securities	0	0
Level 3 | Asset-backed securities | Recurring basis
Assets
Total Debt Securities	0	0
Level 3 | U.S. governmental agency | Recurring basis
Assets
Total Debt Securities	0	0
Level 3 | Residential | Recurring basis
Assets
Total Debt Securities	0	0
Level 3 | Commercial | Recurring basis
Assets
Total Debt Securities	0	0
Level 3 | Large capitalization value | Recurring basis
Assets
Equity securities	0	0
Level 3 | Smaller company growth | Recurring basis
Assets
Equity securities	8	0
Level 3 | REIT | Recurring basis
Assets
Equity securities	0	0
Fair Value Measured on Net Asset Value (NAV) [Member] | Recurring basis
Assets
Equity securities	124	119
Total Assets	124	119
Fair Value Measured on Net Asset Value (NAV) [Member] | REIT | Recurring basis
Assets
Equity securities	124	119
Financial Products | Level 3 | Nonrecurring basis
Assets and liabilities measured on a recurring basis at fair value
Fair value of impaired loans	$ 373	$ 469