Derivative Financial Instruments and Off-balance sheet Financial Instruments - Gross and net amounts for OTC derivatives (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Asset derivatives
Gross amount	$ 142	$ 130
Derivative asset, fair value, gross liability	0	(6)
Net amount on balance sheet	142	124
Liability derivatives
Gross amount	(546)	(281)
Liability derivatives, Gross asset	39	12
Net amount on balance sheet	(507)	(269)
OTC derivatives
Asset derivatives
Gross amount	40	25
Derivative asset, fair value, gross liability	(39)	(18)
Derivative asset, cash collateral (received) pledged	(1)	(5)
Net amount on balance sheet	0	2
Securities collateral (received) pledged	0	0
Net amount	0	2
Liability derivatives
Gross amount	(16)	(12)
Liability derivatives, Gross asset	39	18
Derivative liability offsets under cash collateral pledged	(27)	(12)
Net amount on balance sheet	(4)	(6)
Securities collateral (received) pledged	0	0
Net amount	$ (4)	$ (6)

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