INVESTMENT SECURITIES - Securities Classified as Current and Long-Term (Detail) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Investment [Line Items]
Amortized Cost	$ 10,369	$ 12,104
Gross Unrealized Gains	4	286
Gross Unrealized Losses	(273)	(88)
Fair Value	10,100	12,302
Tax-exempt municipal securities
Investment [Line Items]
Amortized Cost	2,920	3,884
Gross Unrealized Gains	2	33
Gross Unrealized Losses	(65)	(28)
Fair Value	2,857	3,889
Residential mortgage-backed securities
Investment [Line Items]
Amortized Cost	57	26
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(1)	0
Fair Value	56	26
Commercial mortgage-backed securities
Investment [Line Items]
Amortized Cost	528	455
Gross Unrealized Gains	0	3
Gross Unrealized Losses	(18)	(2)
Fair Value	510	456
Asset-backed securities
Investment [Line Items]
Amortized Cost	686	407
Gross Unrealized Gains	0	1
Gross Unrealized Losses	(2)	0
Fair Value	684	408
Corporate debt securities
Investment [Line Items]
Amortized Cost	3,111	5,175
Gross Unrealized Gains	2	244
Gross Unrealized Losses	(93)	(37)
Fair Value	3,020	5,382
U.S. Treasury and other U.S. government corporations and agencies \| U.S. Treasury and agency obligations
Investment [Line Items]
Amortized Cost	649	532
Gross Unrealized Gains	0	1
Gross Unrealized Losses	(5)	(2)
Fair Value	644	531
U.S. Treasury and other U.S. government corporations and agencies \| Mortgage-backed securities
Investment [Line Items]
Amortized Cost	2,418	1,625
Gross Unrealized Gains	0	4
Gross Unrealized Losses	(89)	(19)
Fair Value	$ 2,329	$ 1,610

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Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on 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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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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-Publisher FASB
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Amount 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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