Goodwill and Other Intangible Assets (Details) - Other Intangible Assets - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Other intangible assets by major asset class
Intangible assets subject to amortization, gross carrying amount	$ 301		$ 301		$ 306
Intangible assets subject to amortization, accumulated amortization	192		192		187
Intangible assets subject to amortization, net	109		109		119
Intangible assets not subject to amortization	226		226		226
Total other intangible assets, gross carrying amount	527		527		532
Total other intangible assets, net	335		335		345
Amortization expense of intangible assets	4	$ 4	8	$ 8
Estimated intangible asset amortization expense, remainder of 2019	7		7
Estimated intangible asset amortization expense, 2020	14		14
Estimated intangible asset amortization expense, 2021	13		13
Estimated intangible asset amortization expense, 2022	13		13
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	96		96		98
Intangible assets subject to amortization, accumulated amortization	16		16		12
Intangible assets subject to amortization, net	80		80		86
Contract-based [Member]
Other intangible assets by major asset class
Intangible assets subject to amortization, gross carrying amount	205		205		208
Intangible assets subject to amortization, accumulated amortization	176		176		175
Intangible assets subject to amortization, net	29		29		$ 33
Insurance Contracts Acquired in Business Combination [Member]
Other intangible assets by major asset class
Estimated intangible asset amortization expense, remainder of 2019	3		3
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