Investment Securities (Investment Table) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Schedule of Investments [Line Items]
Debt securities, available-for-sale, fair value	$ 29,989	$ 30,284
Debt securities, held-to-maturity, amortized cost	1,255	1,568
Held-to-maturity securities, fair value	1,336	1,600
Available-for-sale securities
Schedule of Investments [Line Items]
Securities pledged for Federal Home Loan Bank, at fair value	121	1,900
Securities, amount eligible to be repledged or sold by counterparty	121	118
Operating Segments \| Insurance operations \| Available-for-sale securities
Schedule of Investments [Line Items]
Deposit securities	13	12
US Treasury \| Available-for-sale securities
Schedule of Investments [Line Items]
Debt securities, available-for-sale, amortized cost	784	2,059
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	22	6
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	0	(17)
Debt securities, available-for-sale, fair value	806	2,048
US States and political subdivisions \| Available-for-sale securities
Schedule of Investments [Line Items]
Debt securities, available-for-sale, amortized cost	937	623
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	40	19
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	0	(1)
Debt securities, available-for-sale, fair value	977	641
Foreign government \| Available-for-sale securities
Schedule of Investments [Line Items]
Debt securities, available-for-sale, amortized cost	186	184
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	10	3
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	0	(1)
Debt securities, available-for-sale, fair value	196	186
Agency mortgage-backed residential
Schedule of Investments [Line Items]
Debt securities, held-to-maturity, amortized cost	1,249
Agency mortgage-backed residential \| Available-for-sale securities
Schedule of Investments [Line Items]
Debt securities, available-for-sale, amortized cost	19,887	21,183
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	613	257
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	(5)	(36)
Debt securities, available-for-sale, fair value	20,495	21,404
Agency mortgage-backed residential \| Held-to-maturity securities
Schedule of Investments [Line Items]
Debt securities, held-to-maturity, amortized cost	1,249	1,547
Debt securities, held-to-maturity, unrecognized gain	81	38
Debt securities, held-to-maturity, unrecognized loss	0	(6)
Held-to-maturity securities, fair value	1,330	1,579
Mortgage-backed residential \| Available-for-sale securities
Schedule of Investments [Line Items]
Debt securities, available-for-sale, amortized cost	2,982	2,841
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	55	20
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	(1)	(11)
Debt securities, available-for-sale, fair value	3,036	2,850
Agency mortgage-backed commercial \| Available-for-sale securities
Schedule of Investments [Line Items]
Debt securities, available-for-sale, amortized cost	2,115	1,344
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	131	44
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	(2)	(6)
Debt securities, available-for-sale, fair value	2,244	1,382
Mortgage-backed commercial \| Available-for-sale securities
Schedule of Investments [Line Items]
Debt securities, available-for-sale, amortized cost	0	41
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	0	1
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	0	0
Debt securities, available-for-sale, fair value	0	42
Asset-backed
Schedule of Investments [Line Items]
Debt securities, held-to-maturity, amortized cost	6
Asset-backed \| Available-for-sale securities
Schedule of Investments [Line Items]
Debt securities, available-for-sale, amortized cost	384	365
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	5	3
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	0	0
Debt securities, available-for-sale, fair value	389	368
Asset-backed \| Held-to-maturity securities
Schedule of Investments [Line Items]
Debt securities, held-to-maturity, amortized cost	6	21
Debt securities, held-to-maturity, unrecognized gain	0	0
Debt securities, held-to-maturity, unrecognized loss	0	0
Held-to-maturity securities, fair value	6	21
Corporate debt \| Available-for-sale securities
Schedule of Investments [Line Items]
Debt securities, available-for-sale, amortized cost	1,763	1,327
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	88	37
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	(5)	(1)
Debt securities, available-for-sale, fair value	1,846	1,363
Available-for-sale debt securities \| Available-for-sale securities
Schedule of Investments [Line Items]
Debt securities, available-for-sale, amortized cost	29,038	29,967
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	964	390
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	(13)	(73)
Debt securities, available-for-sale, fair value	29,989	30,284
Accrued interest receivable	91	98
Held-to-maturity securities
Schedule of Investments [Line Items]
Debt securities, held-to-maturity, amortized cost	1,255	1,568
Debt securities, held-to-maturity, unrecognized gain	81	38
Debt securities, held-to-maturity, unrecognized loss	0	(6)
Held-to-maturity securities, fair value	1,336	1,600
Accrued interest receivable	3	3
Federal Home Loan Bank certificates and obligations \| Held-to-maturity securities
Schedule of Investments [Line Items]
Securities pledged for Federal Home Loan Bank, at fair value	$ 0	$ 915

Interest, dividends, rents, ancillary and other revenues earned but not yet received by the entity on its investments.

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