Income Tax Returns to be Reviewed (Details)	12 Months Ended
	Dec. 31, 2017
UNITED STATES
Income Tax Examination [Line Items]
Income tax returns to be reviewed	2014
CANADA
Income Tax Examination [Line Items]
Income tax returns to be reviewed	2014
UNITED KINGDOM
Income Tax Examination [Line Items]
Income tax returns to be reviewed	2016
GERMANY
Income Tax Examination [Line Items]
Income tax returns to be reviewed	2013
THE NETHERLANDS
Income Tax Examination [Line Items]
Income tax returns to be reviewed	2012
CHINA
Income Tax Examination [Line Items]
Income tax returns to be reviewed	2008
JAPAN
Income Tax Examination [Line Items]
Income tax returns to be reviewed	2013