Annual report pursuant to Section 13 and 15(d)

Income taxes - Tax Rates (Details)

v3.10.0.1
Income taxes - Tax Rates (Details)
12 Months Ended
Apr. 01, 2017
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Her Majesty's Revenue and Customs (HMRC)        
Income taxes        
Tax rate (as a percent) 19.00% 19.00% 19.25% 20.00%
Internal Revenue Service (IRS)        
Income taxes        
Tax rate (as a percent)   21.00% 34.00% 34.00%