INVESTMENT SECURITIES - Securities Classified as Current and Long-Term (Detail) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Investment [Line Items]
Amortized Cost	$ 11,168	$ 9,826
Gross Unrealized Gains	252	168
Gross Unrealized Losses	(82)	(196)
Fair Value	11,338	9,798
Debt Securities \| Tax-exempt municipal securities
Investment [Line Items]
Amortized Cost	3,457	3,358
Gross Unrealized Gains	28	15
Gross Unrealized Losses	(16)	(68)
Fair Value	3,469	3,305
Debt Securities \| Residential Mortgage-Backed Securities
Investment [Line Items]
Amortized Cost	7	9
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	7	9
Debt Securities \| Commercial Mortgage-Backed Securities
Investment [Line Items]
Amortized Cost	399	307
Gross Unrealized Gains	3	1
Gross Unrealized Losses	(2)	(4)
Fair Value	400	304
Debt Securities \| Asset-backed securities
Investment [Line Items]
Amortized Cost	140	160
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	140	160
Debt Securities \| Corporate debt securities
Investment [Line Items]
Amortized Cost	4,921	3,530
Gross Unrealized Gains	215	145
Gross Unrealized Losses	(37)	(78)
Fair Value	5,099	3,597
Debt Securities \| U.S. Treasury and other U.S. government corporations and agencies \| U.S. Treasury and agency obligations
Investment [Line Items]
Amortized Cost	821	800
Gross Unrealized Gains	1	1
Gross Unrealized Losses	(8)	(15)
Fair Value	814	786
Debt Securities \| U.S. Treasury and other U.S. government corporations and agencies \| Mortgage-backed securities
Investment [Line Items]
Amortized Cost	1,423	1,662
Gross Unrealized Gains	5	6
Gross Unrealized Losses	(19)	(31)
Fair Value	$ 1,409	$ 1,637

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- Definition

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
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- Definition

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
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