Goodwill and Other Intangible Assets (Details) - Other Intangible Assets - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Other intangible assets by major asset class
Intangible assets subject to amortization, gross carrying amount	$ 306	$ 286
Intangible assets subject to amortization, accumulated amortization	187	171
Intangible assets subject to amortization, net	119	115
Intangible assets not subject to amortization	226	227
Total other intangible assets, gross carrying amount	532	513
Total other intangible assets, net	345	342
Amortization expense of intangible assets	17	13	$ 11
Estimated intangible asset amortization expense, 2019	16
Estimated intangible asset amortization expense, 2020	15
Estimated intangible asset amortization expense, 2021	14
Estimated intangible asset amortization expense, 2022	13
Estimated intangible asset amortization expense, 2023	12
Customer-related [Member]
Other intangible assets by major asset class
Intangible assets subject to amortization, gross carrying amount	98	77
Intangible assets subject to amortization, accumulated amortization	12	4
Intangible assets subject to amortization, net	86	73
Contract-based [Member]
Other intangible assets by major asset class
Intangible assets subject to amortization, gross carrying amount	208	209
Intangible assets subject to amortization, accumulated amortization	175	167
Intangible assets subject to amortization, net	33	$ 42
Insurance Contracts Acquired in Business Combination [Member]
Other intangible assets by major asset class
Estimated intangible asset amortization expense, 2019	6
Estimated intangible asset amortization expense, 2020	5
Estimated intangible asset amortization expense, 2021	4
Estimated intangible asset amortization expense, 2022	3
Estimated intangible asset amortization expense, 2023	$ 3