Income Taxes	9 Months Ended
Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Note 6 — Income Taxes Impact of U.S. Tax Reform On December 22, 2017, the U.S. government enacted comprehensive tax legislation, commonly referred to as ‘U.S. Tax Reform’. U.S. Tax Reform makes broad and complex changes to the U.S. tax code, including, but not limited to: (1) requiring a one-time transition tax on certain unremitted earnings of foreign subsidiaries that may be payable over eight years; (2) bonus depreciation that will allow for a full expensing of qualified property; (3) reduction of the federal corporate tax rate from 35% to 21%; (4) a new provision designed to tax global intangible low-taxed income (‘GILTI’), which allows for the possibility of using foreign tax credits (‘FTCs’) and a deduction of up to 50% to offset the income tax liability (subject to some limitations); (5) a new limitation on deductible interest expense; (6) limitations on the deductibility of certain executive compensation; (7) limitations on the use of FTCs to reduce the U.S. income tax liability; (8) the creation of the base erosion anti-abuse tax (‘BEAT’), a new minimum tax; and (9) a general elimination of U.S. federal income taxes on dividends from foreign subsidiaries. Also on December 22, 2017, the SEC staff issued Staff Accounting Bulletin No. 118 (‘SAB 118’), which provides guidance on accounting for the tax effects of the U.S. Tax Reform. SAB 118 provides for a measurement period that should not extend beyond one year from the U.S. Tax Reform enactment date for companies to complete the accounting under Accounting Standards Codification (‘ASC’) 740, Income Taxes (‘ASC 740’). In accordance with SAB 118, a company must reflect the income tax effects of those aspects of U.S. Tax Reform for which the accounting under ASC 740 is complete. Adjustments to incomplete and unknown amounts will be recorded and disclosed prospectively during the measurement period. To the extent that a company’s accounting for certain income tax effects of U.S. Tax Reform is incomplete, but it is able to determine a reasonable estimate, it must record a provisional estimate in its financial statements. If a company cannot determine a provisional estimate to be included in its financial statements, it should continue to apply ASC 740 on the basis of the provisions of the tax laws that were in effect immediately before the enactment of U.S. Tax Reform. As of September 30, 2018, our accounting for U.S. Tax Reform is incomplete. However, as noted in our 2017 Annual Report on Form 10-K, the Company was able to make reasonable estimates of certain effects and recorded provisional adjustments. We expect to complete our accounting within the measurement period for all provisional amounts. For the following provisional items, we did not record any additional measurement period adjustments during the three and nine months ended September 30, 2018, for the following reasons: Reduction of the federal corporate tax rate – The provisional amount of $208 million income tax benefit recorded at December 31, 2017 may be affected due to the continued refinement of our transition tax calculation, additional analysis of tax amounts in other comprehensive income, future guidance issued or other items relating to U.S. Tax Reform. We will continue to analyze and refine our calculations related to the measurement of the deferred tax balances. Indefinite reinvestment assertion – The provisional amount of $1 million for foreign withholding and state income taxes in relation to the future repatriation of earnings previously deemed indefinitely reinvested may be affected by our global working capital and cash requirements. Bonus Depreciation – The provisional tax deduction of $40 million may be affected by the Company’s ongoing analysis of capital expenditures that qualify for immediate expensing. Executive compensation – The provisional income tax expense of $8 million relating to our compensation plans not qualifying for the binding contract exception may be affected by the completion of our analysis of the binding contract requirement on our various compensation plans. For the following provisional items, incremental measurement adjustments were recognized during the nine months ended September 30, 2018 (there were no adjustments made during the three months ended September 30, 2018), but the item is still determined to be provisional for the following reasons: One-time transition tax – The one-time transition tax is based on the Company’s total post-1986 earnings and profits (‘E&P’) that it previously deferred from U.S. income taxes. The Company originally recorded a provisional amount for the ‘one-time’ transition tax liability for its foreign subsidiaries owned by U.S. corporate shareholders, resulting in a U.S. federal income tax expense of $70 million and state income tax expense of $2 million. However, the Internal Revenue Service (‘IRS’) clarified the application of the ‘with’ and ‘without’ approach for calculating the transition tax liability in determining the amount payable over eight years, and as it will appear on the U.S. federal corporate income tax return. Based on this guidance the Company revised its provisional estimate for the U.S. federal transition tax liability in the first quarter of 2018. The provisional amount of U.S. federal transition tax liability was reduced by $64 million due to the utilization of interest loss carryforwards resulting from the transition tax income inclusion. The Company has not made any further measurement period adjustments related to the transition tax since the first quarter of 2018. The Company expects to revise its estimates of E&P, non-U.S. income taxes and cash balances during the fourth quarter of 2018, which could affect the measurement of this liability. Furthermore, additional guidance may be released which could also impact these estimates. GILTI – U.S. Tax Reform creates a new requirement that certain income (i.e., GILTI) earned by controlled foreign corporations (‘CFCs’) must be included currently in the gross income of the CFCs’ U.S. shareholder. The FASB Staff Q&A, Topic 740 No. 5, Accounting for GILTI, states that an entity can make a policy election to either recognize deferred taxes for temporary differences expected to reverse as GILTI in future years or provide for the tax expense related to GILTI resulting from those items in the period the tax is incurred. The Company is treating the taxes due on U.S. inclusions in taxable income related to GILTI as a current-period expense when incurred (the ‘period cost method’) and has included a reasonable estimate of the GILTI in its full-year estimated annual effective tax rate; it is not expected to be material. We will continue to refine our calculations based on future guidance and actual results, which may result in changes to this amount. The Company's accounting for changes in its valuation allowance as a result of U.S. Tax Reform is incomplete, and it is not yet able to make reasonable estimates of the realizability of certain deferred tax assets. The Company must determine whether valuation allowance assessments are affected by various aspects of U.S. Tax Reform (e.g., limitation on net interest expense in excess of 30% of adjusted taxable income). As of September 30, 2018, no provisional adjustments have been recorded. (Benefit from)/provision for income taxes for the three and nine months ended September 30, 2018 was a benefit of $10 million and a provision of $42 million, respectively, compared to provisions of $19 million and $73 million for the three and nine months ended September 30, 2017, respectively. The effective tax rate was (28.1)% and 11.3% for the three and nine months ended September 30, 2018, respectively, and (53.0)% and 17.7% for the three and nine months ended September 30, 2017, respectively. These effective tax rates are calculated using extended values from our condensed consolidated statements of comprehensive income, and are therefore more precise tax rates than can be calculated from rounded values. Historically, our effective tax rate was low as compared to the U.S statutory tax rate of 35% due to our global mix of income and deductions in jurisdictions with high statutory tax rates, primarily the U.S. While the U.S. federal corporate income tax rate has decreased, effective January 1, 2018, from 35% to 21% as a result of U.S. Tax Reform, certain deferred tax benefits realized as a result of the Merger have now been reduced as well. This offsets, in part, the benefit of U.S. Tax Reform, thus increasing our effective income tax rate between the periods. However, the decrease in tax expense for the three and nine months ended September 30, 2018, as compared to the tax expense for the three and nine months ended September 30, 2017, was primarily due to a discrete release of valuation allowance on certain state deferred tax assets. Historically, we provided taxes on the cumulative earnings of certain legacy Towers Watson subsidiaries. The historical cumulative earnings of other legacy Towers Watson subsidiaries have been reinvested indefinitely. However, as a result of U.S. Tax Reform, we have analyzed our global working capital and cash requirements and the potential tax liabilities attributable to a repatriation, and have changed our assertion with respect to certain legacy Towers Watson subsidiaries. For those subsidiaries from which we were able to make a reasonable estimate of the tax effects of such repatriation, we have recorded an estimate for foreign withholding and state income taxes. For all other subsidiaries, we continue to assert that the historical cumulative earnings have been reinvested indefinitely. The Company records valuation allowances against net deferred tax assets based on whether it is more likely than not that the deferred tax assets will be realized. We have liabilities for uncertain tax positions under ASC 740 of $51 million, excluding interest and penalties. The Company believes the outcomes that are reasonably possible within the next 12 months may result in a reduction in the liability for uncertain tax positions of approximately $2 million to $4 million, excluding interest and penalties.

Note 6 — Income Taxes

Impact of U.S. Tax Reform

On December 22, 2017, the U.S. government enacted comprehensive tax legislation, commonly referred to as ‘U.S. Tax Reform’. U.S. Tax Reform makes broad and complex changes to the U.S. tax code, including, but not limited to: (1) requiring a one-time transition tax on certain unremitted earnings of foreign subsidiaries that may be payable over eight years; (2) bonus depreciation that will allow for a full expensing of qualified property; (3) reduction of the federal corporate tax rate from 35% to 21%; (4) a new provision designed to tax global intangible low-taxed income (‘GILTI’), which allows for the possibility of using foreign tax credits (‘FTCs’) and a deduction of up to 50% to offset the income tax liability (subject to some limitations); (5) a new limitation on deductible interest expense; (6) limitations on the deductibility of certain executive compensation; (7) limitations on the use of FTCs to reduce the U.S. income tax liability; (8) the creation of the base erosion anti-abuse tax (‘BEAT’), a new minimum tax; and (9) a general elimination of U.S. federal income taxes on dividends from foreign subsidiaries.

Also on December 22, 2017, the SEC staff issued Staff Accounting Bulletin No. 118 (‘SAB 118’), which provides guidance on accounting for the tax effects of the U.S. Tax Reform. SAB 118 provides for a measurement period that should not extend beyond one year from the U.S. Tax Reform enactment date for companies to complete the accounting under Accounting Standards Codification (‘ASC’) 740, Income Taxes (‘ASC 740’). In accordance with SAB 118, a company must reflect the income tax effects of those aspects of U.S. Tax Reform for which the accounting under ASC 740 is complete. Adjustments to incomplete and unknown amounts will be recorded and disclosed prospectively during the measurement period. To the extent that a company’s accounting for certain income tax effects of U.S. Tax Reform is incomplete, but it is able to determine a reasonable estimate, it must record a provisional estimate in its financial statements. If a company cannot determine a provisional estimate to be included in its financial statements, it should continue to apply ASC 740 on the basis of the provisions of the tax laws that were in effect immediately before the enactment of U.S. Tax Reform.

As of September 30, 2018, our accounting for U.S. Tax Reform is incomplete. However, as noted in our 2017 Annual Report on Form 10-K, the Company was able to make reasonable estimates of certain effects and recorded provisional adjustments. We expect to complete our accounting within the measurement period for all provisional amounts.

For the following provisional items, we did not record any additional measurement period adjustments during the three and nine months ended September 30, 2018, for the following reasons:

Reduction of the federal corporate tax rate – The provisional amount of $208 million income tax benefit recorded at December 31, 2017 may be affected due to the continued refinement of our transition tax calculation, additional analysis of tax amounts in other comprehensive income, future guidance issued or other items relating to U.S. Tax Reform. We will continue to analyze and refine our calculations related to the measurement of the deferred tax balances.

Indefinite reinvestment assertion – The provisional amount of $1 million for foreign withholding and state income taxes in relation to the future repatriation of earnings previously deemed indefinitely reinvested may be affected by our global working capital and cash requirements.

Bonus Depreciation – The provisional tax deduction of $40 million may be affected by the Company’s ongoing analysis of capital expenditures that qualify for immediate expensing.

Executive compensation – The provisional income tax expense of $8 million relating to our compensation plans not qualifying for the binding contract exception may be affected by the completion of our analysis of the binding contract requirement on our various compensation plans.

For the following provisional items, incremental measurement adjustments were recognized during the nine months ended September 30, 2018 (there were no adjustments made during the three months ended September 30, 2018), but the item is still determined to be provisional for the following reasons:

One-time transition tax – The one-time transition tax is based on the Company’s total post-1986 earnings and profits (‘E&P’) that it previously deferred from U.S. income taxes. The Company originally recorded a provisional amount for the ‘one-time’ transition tax liability for its foreign subsidiaries owned by U.S. corporate shareholders, resulting in a U.S. federal income tax expense of $70 million and state income tax expense of $2 million. However, the Internal Revenue Service (‘IRS’) clarified the application of the ‘with’ and ‘without’ approach for calculating the transition tax liability in determining the amount payable over eight years, and as it will appear on the U.S. federal corporate income tax return. Based on this guidance the Company revised its provisional estimate for the U.S. federal transition tax liability in the first quarter of 2018. The provisional amount of U.S. federal transition tax liability was reduced by $64 million due to the utilization of interest loss carryforwards resulting from the transition tax income inclusion. The Company has not made any further measurement period adjustments related to the transition tax since the first quarter of 2018. The Company expects to revise its estimates of E&P, non-U.S. income taxes and cash balances during the fourth quarter of 2018, which could affect the measurement of this liability. Furthermore, additional guidance may be released which could also impact these estimates.

GILTI – U.S. Tax Reform creates a new requirement that certain income (i.e., GILTI) earned by controlled foreign corporations (‘CFCs’) must be included currently in the gross income of the CFCs’ U.S. shareholder. The FASB Staff Q&A, Topic 740 No. 5, Accounting for GILTI, states that an entity can make a policy election to either recognize deferred taxes for temporary differences expected to reverse as GILTI in future years or provide for the tax expense related to GILTI resulting from those items in the period the tax is incurred. The Company is treating the taxes due on U.S. inclusions in taxable income related to GILTI as a current-period expense when incurred (the ‘period cost method’) and has included a reasonable estimate of the GILTI in its full-year estimated annual effective tax rate; it is not expected to be material. We will continue to refine our calculations based on future guidance and actual results, which may result in changes to this amount.

The Company's accounting for changes in its valuation allowance as a result of U.S. Tax Reform is incomplete, and it is not yet able to make reasonable estimates of the realizability of certain deferred tax assets. The Company must determine whether valuation allowance assessments are affected by various aspects of U.S. Tax Reform (e.g., limitation on net interest expense in excess of 30% of adjusted taxable income). As of September 30, 2018, no provisional adjustments have been recorded.

(Benefit from)/provision for income taxes for the three and nine months ended September 30, 2018 was a benefit of $10 million and a provision of $42 million, respectively, compared to provisions of $19 million and $73 million for the three and nine months ended September 30, 2017, respectively. The effective tax rate was (28.1)% and 11.3% for the three and nine months ended September 30, 2018, respectively, and (53.0)% and 17.7% for the three and nine months ended September 30, 2017, respectively. These effective tax rates are calculated using extended values from our condensed consolidated statements of comprehensive income, and are therefore more precise tax rates than can be calculated from rounded values. Historically, our effective tax rate was low as compared to the U.S statutory tax rate of 35% due to our global mix of income and deductions in jurisdictions with high statutory tax rates, primarily the U.S. While the U.S. federal corporate income tax rate has decreased, effective January 1, 2018, from 35% to 21% as a result of U.S. Tax Reform, certain deferred tax benefits realized as a result of the Merger have now been reduced as well. This offsets, in part, the benefit of U.S. Tax Reform, thus increasing our effective income tax rate between the periods. However, the decrease in tax expense for the three and nine months ended September 30, 2018, as compared to the tax expense for the three and nine months ended September 30, 2017, was primarily due to a discrete release of valuation allowance on certain state deferred tax assets.

Historically, we provided taxes on the cumulative earnings of certain legacy Towers Watson subsidiaries. The historical cumulative earnings of other legacy Towers Watson subsidiaries have been reinvested indefinitely. However, as a result of U.S. Tax Reform, we have analyzed our global working capital and cash requirements and the potential tax liabilities attributable to a repatriation, and have changed our assertion with respect to certain legacy Towers Watson subsidiaries. For those subsidiaries from which we were able to make a reasonable estimate of the tax effects of such repatriation, we have recorded an estimate for foreign withholding and state income taxes. For all other subsidiaries, we continue to assert that the historical cumulative earnings have been reinvested indefinitely.

The Company records valuation allowances against net deferred tax assets based on whether it is more likely than not that the deferred tax assets will be realized. We have liabilities for uncertain tax positions under ASC 740 of $51 million, excluding interest and penalties. The Company believes the outcomes that are reasonably possible within the next 12 months may result in a reduction in the liability for uncertain tax positions of approximately $2 million to $4 million, excluding interest and penalties.