Income Taxes	3 Months Ended
Income Taxes	Mar. 31, 2021
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The provision for income taxes is based upon the estimated annual effective tax rates for the year applied to the current period loss before tax plus the tax effect of any significant unusual items, discrete events or changes in tax law. Fluctuations in the distribution of pre-tax income among the Company’s operating subsidiaries can lead to fluctuations of the effective tax rate in the condensed consolidated financial statements. In the three months ended March 31, 2021 and 2020, the actual effective tax rates were 14.4% and 11.0%, respectively. The increase in the effective tax rate for the three months ended March 31, 2021 as compared to the three months ended March 31, 2020 was due an increase in the forecast proportion of qualifying research and development expenditure for the year. The actual effective tax rates are lower than the 19% statutory rate of U.K. tax primarily due to the manner in which the UK research and development credit operates. The tax benefit for the three months ended March 31, 2021 increased to $5.7 million from $3.7 million for three months ended March 31, 2020 due to an increase in pre-tax losses and the increased effective tax rate. The Company carries a $2.0 million deferred tax asset balance related to its U.S. subsidiary. The Company has recorded a valuation allowance against the net deferred tax asset where the recoverability due to future taxable profits is unknown.

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.