Goodwill and Other Intangible Assets (Details) - Other Intangible Assets - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Other intangible assets by major asset class
Intangible assets subject to amortization, gross carrying amount	$ 298		$ 298		$ 306
Intangible assets subject to amortization, accumulated amortization	195		195		187
Intangible assets subject to amortization, net	103		103		119
Intangible assets not subject to amortization	226		226		226
Total other intangible assets, gross carrying amount	524		524		532
Total other intangible assets, net	329		329		345
Amortization expense of intangible assets	4	$ 4	12	$ 12
Estimated intangible asset amortization expense, remainder of 2019	4		4
Estimated intangible asset amortization expense, 2020	14		14
Estimated intangible asset amortization expense, 2021	13		13
Estimated intangible asset amortization expense, 2022	12		12
Estimated intangible asset amortization expense, 2023	12		12
Customer-related [Member]
Other intangible assets by major asset class
Intangible assets subject to amortization, gross carrying amount	94		94		98
Intangible assets subject to amortization, accumulated amortization	18		18		12
Intangible assets subject to amortization, net	76		76		86
Contract-based [Member]
Other intangible assets by major asset class
Intangible assets subject to amortization, gross carrying amount	204		204		208
Intangible assets subject to amortization, accumulated amortization	177		177		175
Intangible assets subject to amortization, net	27		27		$ 33
Insurance Contracts Acquired in Business Combination [Member]
Other intangible assets by major asset class
Estimated intangible asset amortization expense, remainder of 2019	1		1
Estimated intangible asset amortization expense, 2020	5		5
Estimated intangible asset amortization expense, 2021	4		4
Estimated intangible asset amortization expense, 2022	3		3
Estimated intangible asset amortization expense, 2023	$ 3		$ 3