EPS (Calculation of Earnings Per Share and the Reconciliation of Earnings Per Share to Earnings Per Diluted Share) (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Earnings per share:
Net income available to common shareholders	$ 29	$ 760
Less: Income allocated to participating securities	1	8
Net income allocated to common shareholders	28	752
Earnings per diluted share:
Net income available to common shareholders	29	760
Stock-based awards	0	0
Net income available to common shareholders plus assumed conversions	29	760
Less: Income allocated to participating securities	1	8
Net income allocated to common shareholders plus assumed conversions	$ 28	$ 752
Earnings per share:
Net income allocated to common shareholders	713,555,693	661,057,120
Effect of dilutive securities:
Stock-based awards	6,000,000	10,000,000
Net income allocated to common shareholders	720,362,697	670,685,025
Earnings per share:
Earnings per share - basic	$ 0.04	$ 1.14
Earnings per diluted share:
Earnings per share - diluted	$ 0.04	$ 1.12

Net Income Loss Allocated To Common Stockholders Basic.

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Stock-based awards amount.

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The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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