Basis of Presentation and Significant Accounting Policies Impact of Accounting Changes (Details) - USD ($) $ in Millions	Mar. 31, 2020	Jan. 01, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Financing Receivable, before Allowance for Credit Loss		$ 4,215	$ 4,215
Adjusted beginning balance		(19)	0
Financing Receivable, after Allowance for Credit Loss		4,196	4,215
Premiums Receivable, Gross	$ 4,697	4,529	4,529
Premium Receivable, Allowance for Credit Loss	(139)	(122)	(145)
Premiums receivable and agents' balances (net of ACL of {$104} and $145)	4,558	4,407	4,384
Reinsurance Recoverables, Gross	5,713
Reinsurance Recoverable, Allowance for Credit Loss	(52)	(50)	(48)
Reinsurance Recoverables, Including Reinsurance Premium Paid	5,596		5,527
Deferred income taxes, net	502	304	299
Other Liabilities	(4,330)	(5,182)	(5,157)
Retained Earnings (Accumulated Deficit)	12,819	12,667	12,685
Accounting Standards Update 2016-13 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets		2
Premiums Receivable [Member] | Accounting Standards Update 2016-13 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets		0
Premiums Receivable, ACL [Member] | Accounting Standards Update 2016-13 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets		(23)
Reinsurance Recoverable Including Reinsurance Premium Paid, ACL [Member] | Accounting Standards Update 2016-13 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets		2
Deferred Income Tax Asset, Net [Member] | Accounting Standards Update 2016-13 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets		(5)
Other liabilities | Accounting Standards Update 2016-13 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets		25
Total Change to LCL and ACL [Member] | Accounting Standards Update 2016-13 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets		23
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets					$ 0
Retained Earnings | Accounting Standards Update 2016-13 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets		18
Commercial Loan [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Financing Receivable, before Allowance for Credit Loss	4,374		4,215
Adjusted beginning balance	(21)		0	$ (1)	$ (1)
Commercial Loan [Member] | Accounting Standards Update 2016-13 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets		0
Commercial Loan, ACL [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjusted beginning balance		(19)
Commercial Loan, ACL [Member] | Accounting Standards Update 2016-13 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets		(19)
Uncollectible Reinsurance [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reinsurance Recoverables, Gross		5,641	5,641
Reinsurance Recoverable, Allowance for Credit Loss	$ (117)	(116)	(114)
Reinsurance Recoverables, Including Reinsurance Premium Paid		5,525	$ 5,527
Uncollectible Reinsurance [Member] | Reinsurance Recoverable Including Reinsurance Premium Paid [Member] | Accounting Standards Update 2016-13 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets		0
Uncollectible Reinsurance [Member] | Reinsurance Recoverable Including Reinsurance Premium Paid, ACL [Member] | Accounting Standards Update 2016-13 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets		$ 2