DERIVATIVES - Effect of Derivative Instruments on Net Income and Stockholders' Equity (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Amount of net gain (loss) reclassified from OCI to interest expense		$ (329)	$ (202)	$ (856)	$ (536)
Amount Reclassified from AOCI | Net Gain (Loss) Reclassified
Derivative Instruments, Gain (Loss) [Line Items]
Effective portion of (loss) gain recognized in OCI	[1]	(35)	(2)	(122)	35
Amounts of net (loss) gain reclassified from OCI to interest income	[2]	(17)	3	(36)	23
Amount of net gain (loss) reclassified from OCI to interest expense	[2]	$ 3	$ 1	$ 11	$ (2)

[1] The cumulative effective gains and losses on the Company’s cash flow hedging activities are included on the accumulated other comprehensive loss line item on the Consolidated Balance Sheets.

[2] This amount includes both (i) the amortization of effective gains and losses associated with the Company’s terminated cash flow hedges and (ii) the current reporting period’s interest settlements realized on the Company’s active cash flow hedges. Both (i) and (ii) were previously included on the accumulated other comprehensive loss line item on the Consolidated Balance Sheets and were subsequently recorded as adjustments to the interest income or expense of the underlying hedged item.