Goodwill and Other Intangible Assets (Details) - Other Intangible Assets - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Other intangible assets by major asset class
Intangible assets subject to amortization, gross carrying amount	$ 310		$ 306
Intangible assets subject to amortization, accumulated amortization	219		215
Intangible assets subject to amortization, net	91		91
Intangible assets not subject to amortization	227		226
Total other intangible assets, gross carrying amount	537		532
Total other intangible assets, net	318		317
Amortization expense of intangible assets	4	$ 4
Estimated intangible asset amortization expense, remainder of 2021	11
Estimated intangible asset amortization expense, 2022	14
Estimated intangible asset amortization expense, 2023	13
Estimated intangible asset amortization expense, 2024	13
Estimated intangible asset amortization expense, 2025	12
Customer-related [Member]
Other intangible assets by major asset class
Intangible assets subject to amortization, gross carrying amount	105		101
Intangible assets subject to amortization, accumulated amortization	34		31
Intangible assets subject to amortization, net	71		70
Contract-based [Member]
Other intangible assets by major asset class
Intangible assets subject to amortization, gross carrying amount	205		205
Intangible assets subject to amortization, accumulated amortization	185		184
Intangible assets subject to amortization, net	20		$ 21
Insurance Contracts Acquired in Business Combination [Member]
Other intangible assets by major asset class
Estimated intangible asset amortization expense, remainder of 2021	3
Estimated intangible asset amortization expense, 2022	3
Estimated intangible asset amortization expense, 2023	3
Estimated intangible asset amortization expense, 2024	2
Estimated intangible asset amortization expense, 2025	$ 2