Securities - Amortized Cost, Gross Unrealized Gains, Gross Unrealized Losses, and Fair Values of Securities (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Securities available for sale
Amortized Cost	$ 16,061	$ 17,808
Gross Unrealized Gains	646	126
Gross Unrealized Losses	37	145
Securities Available for Sale	16,670	17,789
U.S. Treasury and government agencies
Securities available for sale
Amortized Cost	3,048	5,485
Gross Unrealized Gains	234	6
Gross Unrealized Losses	0	53
Securities Available for Sale	3,282	5,438
U.S. agencies
Securities available for sale
Amortized Cost	5,390	5,491
Gross Unrealized Gains	74	13
Gross Unrealized Losses	3	36
Securities Available for Sale	5,461	5,468
Residential - non-agency
Securities available for sale
Amortized Cost	648	759
Gross Unrealized Gains	8	5
Gross Unrealized Losses	1	2
Securities Available for Sale	655	762
Commercial - non-agency
Securities available for sale
Amortized Cost	4,151	3,461
Gross Unrealized Gains	283	56
Gross Unrealized Losses	8	28
Securities Available for Sale	4,426	3,489
Collateralized loan obligations
Securities available for sale
Amortized Cost	1,387	1,499
Gross Unrealized Gains	0	0
Gross Unrealized Losses	16	8
Securities Available for Sale	1,371	1,491
Direct bank purchase bonds
Securities available for sale
Amortized Cost	901	911
Gross Unrealized Gains	45	43
Gross Unrealized Losses	9	18
Securities Available for Sale	937	936
Other
Securities available for sale
Amortized Cost	536	202
Gross Unrealized Gains	2	3
Gross Unrealized Losses	0	0
Securities Available for Sale	$ 538	$ 205

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

No definition available.

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- Definition

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563

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- Definition

Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

No definition available.

+ Details

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- Definition

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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