Investments (Schedule Of Investments In Partially-Owned Insurance Companies) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Investment [Line Items]
Document Period End Date	Dec. 31, 2019
Carrying Value	$ 1,332	$ 678
Huatai Group [Member]
Investment [Line Items]
Ownership Percentage	30.90%	20.00%
Huatai Group [Member] | CHINA
Investment [Line Items]
Carrying Value	$ 1,053	$ 452
Ownership Percentage	31.00%	20.00%
Huatai Life Insurance Co. [Member] | CHINA
Investment [Line Items]
Carrying Value	$ 147	$ 106
Ownership Percentage	20.00%	20.00%
Freisenbruch-Meyer | Bermuda
Investment [Line Items]
Carrying Value	$ 10	$ 9
Ownership Percentage	40.00%	40.00%
Chubb Arabia Cooperative Insurance Company [Member] | Saudi Arabia
Investment [Line Items]
Carrying Value	$ 20	$ 18
Ownership Percentage	30.00%	30.00%
Russian Reinsurance Company | Russia
Investment [Line Items]
Carrying Value	$ 2	$ 2
Ownership Percentage	23.00%	23.00%
ABR Reinsurance Capital Holdings Ltd. [Member] | Bermuda
Investment [Line Items]
Carrying Value	$ 100	$ 91
Ownership Percentage	12.00%	12.00%
Direct Ownership [Member] | Huatai Life Insurance Co. [Member] | CHINA
Investment [Line Items]
Ownership Percentage	20.00%
Indirect Ownership [Member] | Huatai Group [Member] | CHINA
Investment [Line Items]
Ownership Percentage	30.90%
Indirect Ownership [Member] | Huatai Life Insurance Co. [Member] | CHINA
Investment [Line Items]
Ownership Percentage	25.00%
Total Direct and Indirect [Member] | Huatai Life Insurance Co. [Member] | CHINA
Investment [Line Items]
Ownership Percentage	45.00%