INVESTMENTS - Fair Value of AFS Debt Securities by Contractual Maturity Date (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Fair value
Total fair value	$ 275,425	$ 288,038
Mortgage-backed securities
Amoritzed cost
Amortized cost, due within 1 year	15	14
Amortized cost, after 1 but within 5 years	564	662
Amortized cost, after 5 but within 10 years	1,738	2,779
Amortized cost, after 10 years	37,292	41,533
Amortized cost	39,609	44,988
Fair value
Fair value, due within 1 year	15	14
Fair value, after 1 but within 5 years	565	661
Fair value, after 5 but within 10 years	1,908	2,828
Fair value, after 10 years	37,591	41,002
Total fair value	40,079	44,505
U.S. Treasury and federal agency securities
Amoritzed cost
Amortized cost, due within 1 year	51,529	41,941
Amortized cost, after 1 but within 5 years	56,986	76,139
Amortized cost, after 5 but within 10 years	137	489
Amortized cost, after 10 years	25	90
Amortized cost	108,677	118,659
Fair value
Fair value, due within 1 year	51,392	41,867
Fair value, after 1 but within 5 years	56,673	74,800
Fair value, after 5 but within 10 years	138	462
Fair value, after 10 years	30	93
Total fair value	108,233	117,222
State and municipal securities
Amoritzed cost
Amortized cost, due within 1 year	1,255	2,586
Amortized cost, after 1 but within 5 years	1,100	1,676
Amortized cost, after 5 but within 10 years	290	585
Amortized cost, after 10 years	3,352	4,525
Amortized cost	5,997	9,372
Fair value
Fair value, due within 1 year	1,105	2,586
Fair value, after 1 but within 5 years	973	1,675
Fair value, after 5 but within 10 years	266	602
Fair value, after 10 years	3,610	4,343
Total fair value	5,954	9,206
Foreign government
Amoritzed cost
Amortized cost, due within 1 year	40,374	39,078
Amortized cost, after 1 but within 5 years	54,451	50,125
Amortized cost, after 5 but within 10 years	8,648	10,153
Amortized cost, after 10 years	1,568	1,516
Amortized cost	105,041	100,872
Fair value
Fair value, due within 1 year	40,409	39,028
Fair value, after 1 but within 5 years	54,750	49,962
Fair value, after 5 but within 10 years	8,763	10,149
Fair value, after 10 years	1,607	1,552
Total fair value	105,529	100,691
All other
Amoritzed cost
Amortized cost, due within 1 year	6,609	6,166
Amortized cost, after 1 but within 5 years	8,129	8,459
Amortized cost, after 5 but within 10 years	731	1,474
Amortized cost, after 10 years	185	433
Amortized cost	15,654	16,532
Fair value
Fair value, due within 1 year	6,612	6,166
Fair value, after 1 but within 5 years	8,140	8,416
Fair value, after 5 but within 10 years	719	1,427
Fair value, after 10 years	159	405
Total fair value	$ 15,630	$ 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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