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Income taxes - Additional Information (Detail) - USD ($)
 12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Tax Credit Carryforward [Line Items]      
Income tax benefit, principally related to Tax Cuts and Jobs Act   $ 50,400,000  
Rate change in the company's income tax provision $ (2,300,000) (400,000) $ 3,500,000
Net financial statement impact due to valuation allowance recorded against all U.S. deferred tax assets   0  
Provision for income taxes that may become payable upon distribution of earnings of certain foreign subsidiaries 0    
Unrecognized deferred income tax liability 25,300,000    
Penalties and interest accrued related to income tax liabilities 2,600,000 $ 2,300,000  
Utilization of tax attributes, annual limitation 70,600,000    
Utilization of tax attributes, cumulative limitation $ 454,900,000    
Minimum      
Tax Credit Carryforward [Line Items]      
Expected change in ownership percentage 50.00%    
Netherlands      
Tax Credit Carryforward [Line Items]      
Rate change in the company's income tax provision     (2,200,000)
UK      
Tax Credit Carryforward [Line Items]      
Rate change in the company's income tax provision     $ 3,500,000