Goodwill and Other Intangible Assets (Details) - Other Intangible Assets - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Other intangible assets by major asset class
Intangible assets subject to amortization, gross carrying amount	$ 304		$ 306
Intangible assets subject to amortization, accumulated amortization	189		187
Intangible assets subject to amortization, net	115		119
Intangible assets not subject to amortization	226		226
Total other intangible assets, gross carrying amount	530		532
Total other intangible assets, net	341		345
Amortization expense of intangible assets	4	$ 4
Estimated intangible asset amortization expense, remainder of 2019	12
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	100		98
Intangible assets subject to amortization, accumulated amortization	15		12
Intangible assets subject to amortization, net	85		86
Contract-based [Member]
Other intangible assets by major asset class
Intangible assets subject to amortization, gross carrying amount	204		208
Intangible assets subject to amortization, accumulated amortization	174		175
Intangible assets subject to amortization, net	30		$ 33
Insurance Contracts Acquired in Business Combination [Member]
Other intangible assets by major asset class
Estimated intangible asset amortization expense, remainder of 2019	4
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