CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) (Parenthetical) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statement of Comprehensive Income [Abstract]
Net unrealized derivative instrument gains (losses) arising during the periods, tax	$ 23		$ 36
Net unrealized derivative instrument gains (losses) arising during the periods, tax, before 2017-12 adoption		$ (4)		$ (22)
Reclassification adjustment for net derivative losses included in net income, tax	4		9
Reclassification adjustment for net derivative losses included in net income, tax, before 2017-12 adoption		3		3
Net unrealized debt securities gains (losses) arising during the periods, tax	72	(19)	152	(105)
Other-than-temporary impairment not recognized in earnings on debt securities, tax	0	1	0	0
Reclassification of net debt securities gains to net income, tax	(1)	0	(3)	(2)
Amortization of actuarial loss, tax	$ 1	$ 1	$ 3	$ 2

Amount, before reclassification, of tax expense (benefit) for gain (loss) from derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness.

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Amount of tax expense (benefit) for reclassification of gain (loss) from accumulated other comprehensive income (AOCI) for derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness.

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Amount of tax expense (benefit) of reclassification adjustment from accumulated other comprehensive income for unrealized gain (loss) realized upon the sale of available-for-sale securities.

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Amount of tax expense (benefit) of reclassification adjustment from accumulated other comprehensive income of accumulated gain (loss) realized from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's deferred hedging gain (loss).

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Amount of tax expense (benefit), before reclassification adjustments, related to increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

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Amount of tax expense (benefit) before reclassification adjustments of unrealized holding gain (loss) on available-for-sale securities.

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Amount of tax (expense) benefit of other than temporary impairment loss (OTTI) on investments in available-for-sale and held-to-maturity debt securities, recognized in other comprehensive loss and attributable to parent entity.

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