Pension Pension (Narrative) (Details) - USD ($)	3 Months Ended	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plan, Cost		$ 3,600,000	$ 3,400,000	$ 3,400,000
NETHERLANDS | Non-U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Employer contributions due to the unwinding of Dutch defined benefit pension plan	$ 5,200,000
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position	0			$ 0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	$ (21,600,000)
Defined Contribution Plan, Cost		$ 1,900,000	$ 1,900,000