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Investment Securities - Realized Gains and Losses on Securities and OTTI Recognized in Earnings (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Realized gains (losses):
Gross realized gains	$ 44	$ 13	$ 144
Gross realized losses	(18)	(21)	(74)
Net realized gains (losses)	26	(8)	70
OTTI recognized in earnings:
Credit related OTTI	0	(1)	(2)
Intent-to-sell OTTI	0	(200)	(3)
Total OTTI recognized in earnings	0	(201)	(5)
Net securities gains (losses)	26	(209)	65
Total proceeds from sales	$ 4,780	$ 6,399	$ 8,181

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Amount of realized gain on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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