Other Intangible Assets (Summary of Other Intangible Assets) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Schedule of Other Intangible Assets [Abstract]
Finite-lived intangible assets	$ 16	$ 18
Intangible Assets, Gross (Excluding Goodwill)	77	81
Indefinite-lived intangible assets	61	63
Accumulated amortization	9	9
Syndicate capacity
Schedule of Other Intangible Assets [Abstract]
Indefinite-lived intangible assets	45	47
Agency force
Schedule of Other Intangible Assets [Abstract]
Indefinite-lived intangible assets	$ 16	16
Trade Names
Schedule of Other Intangible Assets [Abstract]
Economic useful life measured in years	8 years
Finite-lived intangible assets	$ 6	7
Accumulated amortization	$ 5	5
Distribution channel
Schedule of Other Intangible Assets [Abstract]
Economic useful life measured in years	15 years
Finite-lived intangible assets	$ 10	11
Accumulated amortization	$ 4	$ 4