SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Accounting Changes (Details) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
		Dec. 31, 2017	Dec. 31, 2017	Jan. 01, 2017	Dec. 31, 2016	Jan. 01, 2016	Dec. 31, 2015	Dec. 31, 2014
New Accounting Pronouncements or Change in Accounting Principle
Impact of non-cash charge related to Tax Reform		$ 22,600	$ 22,594
Charge related to remeasurement due to reduction of tax rate		12,400
Reduction in FTC carry-forwards that relate to deemed repatriation		2,300
Charge related to reduction in U.S. tax rate		6,200
Charge related to reduction in corporate tax rate for which accounting is complete		6,200
Retained earnings		138,425	138,425		$ 146,477
Stockholders’ equity		201,672	201,672		226,143		$ 223,092
Increase (decrease) to AOCI		(34,668)	(34,668)		(32,381)
Accounting Standards Update 2018-02
New Accounting Pronouncements or Change in Accounting Principle
Retained earnings		3,300	3,300
Cumulative effect of new accounting principle		(3,304)	(3,304)
Accounting Standards Update 2017-08 | New Accounting Pronouncement, Early Adoption, Effect
New Accounting Pronouncements or Change in Accounting Principle
Stockholders’ equity				$ (156)
Accounting Standards Update 2016-01
New Accounting Pronouncements or Change in Accounting Principle
Retained earnings						$ 15
Increase (decrease) to AOCI						(15)
Accounting Standards Update 2016-01 | New Accounting Pronouncement, Early Adoption, Effect
New Accounting Pronouncements or Change in Accounting Principle
Increase (decrease) to AOCI						$ (15)
Foreign Tax Credit Carryforwards
New Accounting Pronouncements or Change in Accounting Principle
Valuation allowance		7,900	7,900
Retained earnings
New Accounting Pronouncements or Change in Accounting Principle
Stockholders’ equity		138,425	138,425		146,477		133,841	$ 117,852
Cumulative effect of new accounting principle	[1]				(660)		15
Retained earnings | Accounting Standards Update 2017-08 | New Accounting Pronouncement, Early Adoption, Effect
New Accounting Pronouncements or Change in Accounting Principle
Cumulative effect of new accounting principle				(660)
Accumulated other comprehensive income (loss)
New Accounting Pronouncements or Change in Accounting Principle
Stockholders’ equity		(34,668)	(34,668)		(32,381)		(29,344)	(23,216)
Cumulative effect of new accounting principle	[1]				504		(15)
Increase (decrease) to AOCI		$ (34,668)	$ (34,668)		$ (32,381)		$ (29,344)	$ (23,216)
Accumulated other comprehensive income (loss) | Accounting Standards Update 2017-08 | New Accounting Pronouncement, Early Adoption, Effect
New Accounting Pronouncements or Change in Accounting Principle
Cumulative effect of new accounting principle				$ 504

[1] See Note 1 to the Consolidated Financial Statements.