Securities - Schedule of Available For Sale Securities (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Securities available for sale
Amortized Cost	$ 16,680	$ 17,794
Gross Unrealized Gains	41	58
Gross Unrealized Losses	407	289
Fair Value	16,314	17,563
U.S. Treasury
Securities available for sale
Amortized Cost	3,572	3,370
Gross Unrealized Gains	1	0
Gross Unrealized Losses	144	118
Fair Value	3,429	3,252
U.S. government agency and government-sponsored agencies
Securities available for sale
Amortized Cost	8,168	9,338
Gross Unrealized Gains	7	2
Gross Unrealized Losses	168	132
Fair Value	8,007	9,208
Privately issued
Securities available for sale
Amortized Cost	887	695
Gross Unrealized Gains	0	3
Gross Unrealized Losses	23	4
Fair Value	864	694
Privately issued - commercial mortgage-backed securities
Securities available for sale
Amortized Cost	1,179	823
Gross Unrealized Gains	3	4
Gross Unrealized Losses	20	5
Fair Value	1,162	822
Collateralized loan obligations
Securities available for sale
Amortized Cost	1,492	1,895
Gross Unrealized Gains	0	10
Gross Unrealized Losses	18	0
Fair Value	1,474	1,905
Other
Securities available for sale
Amortized Cost	4	5
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	4	5
Asset Liability Management securities
Securities available for sale
Amortized Cost	15,302	16,126
Gross Unrealized Gains	11	19
Gross Unrealized Losses	373	259
Fair Value	14,940	15,886
Direct bank purchase bonds
Securities available for sale
Amortized Cost	1,190	1,495
Gross Unrealized Gains	30	38
Gross Unrealized Losses	30	30
Fair Value	1,190	1,503
Other
Securities available for sale
Amortized Cost	188	163
Gross Unrealized Gains	0	1
Gross Unrealized Losses	4	0
Fair Value	$ 184	164
Equity securities
Securities available for sale
Amortized Cost		10
Gross Unrealized Gains		0
Gross Unrealized Losses		0
Fair Value		$ 10

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

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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

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