INVESTMENTS - Fair Value of AFS Debt Securities by Contractual Maturity Date (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Amoritzed cost
Investments	$ 398,883	$ 368,563
Fair value
Total fair value	308,219	280,265
Mortgage-backed securities
Amoritzed cost
Amortized cost, due within 1 year	629	20
Amortized cost, after 1 but within 5 years	584	573
Amortized cost, after 5 but within 10 years	1,009	594
Amortized cost, after 10 years	41,158	34,640
Amortized cost	43,380	35,827
Fair value
Fair value, due within 1 year	640	20
Fair value, after 1 but within 5 years	585	574
Fair value, after 5 but within 10 years	1,067	626
Fair value, after 10 years	42,081	34,877
Total fair value	44,373	36,097
U.S. Treasury and federal agency securities
Amoritzed cost
Amortized cost, due within 1 year	27,233	40,757
Amortized cost, after 1 but within 5 years	88,605	70,128
Amortized cost, after 5 but within 10 years	6,515	854
Amortized cost, after 10 years	25	26
Amortized cost	122,378	111,765
Fair value
Fair value, due within 1 year	27,403	40,688
Fair value, after 1 but within 5 years	91,130	69,850
Fair value, after 5 but within 10 years	6,697	851
Fair value, after 10 years	32	29
Total fair value	125,262	111,418
State and municipal securities
Amoritzed cost
Amortized cost, due within 1 year	937	932
Amortized cost, after 1 but within 5 years	601	714
Amortized cost, after 5 but within 10 years	291	195
Amortized cost, after 10 years	3,848	3,183
Amortized cost	5,677	5,024
Fair value
Fair value, due within 1 year	937	932
Fair value, after 1 but within 5 years	608	723
Fair value, after 5 but within 10 years	312	215
Fair value, after 10 years	3,608	3,108
Total fair value	5,465	4,978
Foreign government
Amoritzed cost
Amortized cost, due within 1 year	46,369	42,611
Amortized cost, after 1 but within 5 years	59,050	58,820
Amortized cost, after 5 but within 10 years	9,481	8,192
Amortized cost, after 10 years	1,803	1,335
Amortized cost	116,703	110,958
Fair value
Fair value, due within 1 year	46,491	42,666
Fair value, after 1 but within 5 years	59,561	59,071
Fair value, after 5 but within 10 years	9,505	8,198
Fair value, after 10 years	1,810	1,368
Total fair value	117,367	111,303
All other
Amoritzed cost
Amortized cost, due within 1 year	5,836	7,306
Amortized cost, after 1 but within 5 years	8,894	8,279
Amortized cost, after 5 but within 10 years	921	818
Amortized cost, after 10 years	157	116
Amortized cost	15,808	16,519
Fair value
Fair value, due within 1 year	5,846	7,311
Fair value, after 1 but within 5 years	8,908	8,275
Fair value, after 5 but within 10 years	891	797
Fair value, after 10 years	107	86
Total fair value	$ 15,752	$ 16,469

Sum of the carrying amounts as of the balance sheet date of all investments, excluding trading account assets.

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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