Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Tax Disclosure [Abstract]
Income tax benefit	$ (49)	$ (84)	$ (70)	$ (63)
Effective income tax rate	30.00%	215.00%	29.00%	394.00%
Nondeductible expenses	$ 19
Settlement of a client claim			$ 18
Favorable court ruling on tax matters			19
Nondeductible, state tax and other expenses			12
Unrecognized tax benefits decreased			$ 19

Income tax reconciliation nondeductible expense state and other.

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to increase (decrease) in income tax contingencies. Including, but not limited to, domestic tax contingency, foreign tax contingency, state and local tax contingency, and other contingencies.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to income tax settlements. Including, but not limited to, domestic tax settlement, foreign tax settlement, state and local tax settlement, and other tax settlements.

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Amount of decrease in unrecognized tax benefits resulting from settlements with taxing authorities.

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