Fair Value - Narrative (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Fair value, assets, level 2 to level 1, transfers	$ 0	$ 0	$ 0	$ 0
Fair value, assets, level 1 to level 2, transfers	0	$ 0	0	$ 0
Other invested assets overseas deposit	37,000,000		$ 37,000,000		$ 31,000,000
Life settlement contracts, receivable, payment period			3 years
Life settlement contracts, fair value	$ 0		$ 0		$ 58,000,000