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Income Taxes - Additional Information (Details) - USD ($)
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Operating Loss Carryforwards [Line Items]      
Reductions due to expiry of statute of limitations, gross $ 200,000    
Reductions due to expiry of statute of limitations may be recognized by the end of 2019 100,000    
Unrecognized tax benefits that would impact effective tax rate 700,000 $ 700,000 $ 600,000
Unrecognized tax benefits, income tax penalties and interest expense 0 0 0
Undistributed earnings of foreign subsidiaries 47,200,000 62,400,000 59,000,000.0
Deferred tax liability not recognized, amount of unrecognized deferred tax liability, undistributed earnings of foreign subsidiaries 700,000 600,000 300,000
Tax losses and tax credit carryforward, amount 94,900,000 81,000,000.0 92,700,000
Tax losses and tax credit carryforward, valuation allowance 14,900,000 15,000,000.0 15,000,000.0
U.K.      
Operating Loss Carryforwards [Line Items]      
Tax losses and tax credit carryforward, amount 32,800,000 38,800,000 43,400,000
Tax losses and tax credit carryforward, valuation allowance 2,800,000 4,100,000 4,600,000
Non-U.K.      
Operating Loss Carryforwards [Line Items]      
Tax losses and tax credit carryforward, amount 62,100,000 42,200,000 49,300,000
Tax losses and tax credit carryforward, valuation allowance 12,100,000 $ 10,900,000 $ 10,400,000
Tax Losses And Tax Credits Carryforward, Expire Between 2023 and 2034      
Operating Loss Carryforwards [Line Items]      
Tax losses and tax credit carryforward, amount 26,400,000    
Tax Losses And Tax Credits Carryforward, Indefinite      
Operating Loss Carryforwards [Line Items]      
Tax losses and tax credit carryforward, amount $ 68,500,000