Goodwill and Other Intangibles - Narrative (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Changes in the goodwill balance during the period			$ 0
Goodwill	$ 199,000,000		199,000,000		$ 199,000,000
Amortizable intangible assets related to property and casualty insurance acquisitions	29,000,000		29,000,000		34,000,000
Accumulated amortization	28,000,000		28,000,000		$ 25,000,000
Amortization of intangible assets	$ 2,000,000	$ 2,000,000	$ 6,000,000	$ 6,000,000