INVESTMENT SECURITIES - Schedule of Investment Securities Classified as Current and Long-Term (Detail) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Investment [Line Items]
Amortized Cost	$ 10,641	$ 12,104
Gross Unrealized Gains	9	286
Gross Unrealized Losses	(213)	(88)
Fair Value	10,437	12,302
U.S. Treasury and agency obligations \| U.S. Treasury and other U.S. government corporations and agencies
Investment [Line Items]
Amortized Cost	419	532
Gross Unrealized Gains	1	1
Gross Unrealized Losses	(3)	(2)
Fair Value	417	531
Mortgage-backed securities \| U.S. Treasury and other U.S. government corporations and agencies
Investment [Line Items]
Amortized Cost	2,595	1,625
Gross Unrealized Gains	3	4
Gross Unrealized Losses	(54)	(19)
Fair Value	2,544	1,610
Tax-exempt municipal securities
Investment [Line Items]
Amortized Cost	2,805	3,884
Gross Unrealized Gains	3	33
Gross Unrealized Losses	(37)	(28)
Fair Value	2,771	3,889
Residential Mortgage-backed securities
Investment [Line Items]
Amortized Cost	55	26
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	55	26
Commercial Mortgage-backed securities
Investment [Line Items]
Amortized Cost	537	455
Gross Unrealized Gains	0	3
Gross Unrealized Losses	(14)	(2)
Fair Value	523	456
Asset-backed securities
Investment [Line Items]
Amortized Cost	991	407
Gross Unrealized Gains	1	1
Gross Unrealized Losses	(7)	0
Fair Value	985	408
Corporate debt securities
Investment [Line Items]
Amortized Cost	3,239	5,175
Gross Unrealized Gains	1	244
Gross Unrealized Losses	(98)	(37)
Fair Value	$ 3,142	$ 5,382

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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).

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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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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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