INVESTMENTS - Fair Value of AFS Debt Securities by Contractual Maturity Date (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Amoritzed cost
Amortized cost	$ 275,989	$ 290,423
Fair value
Total fair value	275,132	288,038
Mortgage-backed securities
Amoritzed cost
Amortized cost, due within 1 year	68	14
Amortized cost, after 1 but within 5 years	706	662
Amortized cost, after 5 but within 10 years	1,824	2,779
Amortized cost, after 10 years	37,886	41,533
Amortized cost	40,484	44,988
Fair value
Fair value, due within 1 year	68	14
Fair value, after 1 but within 5 years	707	661
Fair value, after 5 but within 10 years	1,922	2,828
Fair value, after 10 years	37,895	41,002
Total fair value	40,592	44,505
U.S. Treasury and federal agency securities
Amoritzed cost
Amortized cost, due within 1 year	39,674	41,941
Amortized cost, after 1 but within 5 years	68,442	76,139
Amortized cost, after 5 but within 10 years	597	489
Amortized cost, after 10 years	26	90
Amortized cost	108,739	118,659
Fair value
Fair value, due within 1 year	39,554	41,867
Fair value, after 1 but within 5 years	67,520	74,800
Fair value, after 5 but within 10 years	573	462
Fair value, after 10 years	26	93
Total fair value	107,673	117,222
State and municipal securities
Amoritzed cost
Amortized cost, due within 1 year	1,674	2,586
Amortized cost, after 1 but within 5 years	1,542	1,676
Amortized cost, after 5 but within 10 years	573	585
Amortized cost, after 10 years	4,223	4,525
Amortized cost	8,012	9,372
Fair value
Fair value, due within 1 year	1,673	2,586
Fair value, after 1 but within 5 years	1,546	1,675
Fair value, after 5 but within 10 years	595	602
Fair value, after 10 years	4,295	4,343
Total fair value	8,109	9,206
Foreign government
Amoritzed cost
Amortized cost, due within 1 year	41,824	39,078
Amortized cost, after 1 but within 5 years	46,950	50,125
Amortized cost, after 5 but within 10 years	11,034	10,153
Amortized cost, after 10 years	1,488	1,516
Amortized cost	101,296	100,872
Fair value
Fair value, due within 1 year	41,806	39,028
Fair value, after 1 but within 5 years	46,936	49,962
Fair value, after 5 but within 10 years	11,083	10,149
Fair value, after 10 years	1,531	1,552
Total fair value	101,356	100,691
All other
Amoritzed cost
Amortized cost, due within 1 year	6,867	6,166
Amortized cost, after 1 but within 5 years	8,199	8,459
Amortized cost, after 5 but within 10 years	1,429	1,474
Amortized cost, after 10 years	963	433
Amortized cost	17,458	16,532
Fair value
Fair value, due within 1 year	6,865	6,166
Fair value, after 1 but within 5 years	8,188	8,416
Fair value, after 5 but within 10 years	1,410	1,427
Fair value, after 10 years	939	405
Total fair value	$ 17,402	$ 16,414

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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