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Discontinued Operations - Schedule of Gain on Divestiture within Income from Discontinued Operations (Detail) - USD ($) $ in Millions | 1 Months Ended | 12 Months Ended
--- | --- | ---
Aug. 31, 2015 | Dec. 31, 2015
Discontinued Operations and Disposal Groups [Abstract] |  |
Proceeds on disposal, net of transaction costs | $ 549 |
Net assets disposed | 438 |
Pretax gain on divestiture | 111 |
Income taxes | 66 |
Gain on divestiture, net of tax | $ 45 | $ 45

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