Derivative Financial Instruments - Gross and Net Amounts Derivatives (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Asset derivatives
Gross amount	$ 85	$ 30
Counter- party netting	0	(2)
Net amount on balance sheet	85	28
Liability derivatives
Gross amount	(441)	(228)
Counter- party netting	9	1
Net amount on balance sheet	(432)	(227)
OTC derivatives
Asset derivatives
Gross amount	10	10
Counter- party netting	(9)	(3)
Cash collateral (received) pledged	0	(5)
Net amount on balance sheet	1	2
Securities collateral (received) pledged	0	0
Net amount	1	2
Liability derivatives
Gross amount	(2)	(2)
Counter- party netting	9	3
Cash collateral (received) pledged	(8)	(1)
Net amount on balance sheet	(1)	0
Securities collateral (received) pledged	0	0
Net amount	$ (1)	$ 0

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