Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income tax expense relating to above	$ (125)	$ (62)
Accumulated other comprehensive loss	(84,892)	(83,467)
Cumulative foreign currency translation loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI before tax	(87,591)	(84,105)
Unrealized gain/(loss) on cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI before tax	4,604	(218)
Retirement benefits
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI before tax	$ (1,780)	$ 918