Investments - Investments - ACL on Mortgages (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Jan. 01, 2020
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance	$ 0
Adjusted beginning balance	0		$ (19)
Accounting Standards Update 2016-13 [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets			2
Commercial Loan [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance	0	$ (1)
Adjusted beginning balance	(21)	(1)
Current period provision	(2)	0
Ending balance	$ (21)	$ (1)
Commercial Loan [Member] | Accounting Standards Update 2016-13 [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets			0
Commercial Loan, ACL [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Adjusted beginning balance			(19)
Commercial Loan, ACL [Member] | Accounting Standards Update 2016-13 [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets			$ (19)