Retirement Plans - Assumptions used (Details)	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015
US Plan
Net benefit cost - weighted average assumptions
Discount rate	4.25%	3.91%
Expected long-term rate of return on plan assets	6.00%	6.00%
Benefit obligation - weighted-average assumptions
Discount rate	4.04%	4.25%
UK Plans
Net benefit cost - weighted average assumptions
Discount rate	2.74%	3.70%
Expected long-term rate of return on plan assets	2.77%	3.48%
Rate of compensation increase	3.62%	3.96%
Benefit obligation - weighted-average assumptions
Discount rate	2.76%	3.70%
Rate of compensation increase	3.62%	3.96%
Europe plans
Net benefit cost - weighted average assumptions
Discount rate	1.33%	2.42%
Rate of compensation increase	2.50%	2.50%
Benefit obligation - weighted-average assumptions
Discount rate	1.33%	2.42%
Rate of compensation increase	2.50%	2.50%

The interest rate used to adjust for the time value of money for the plan.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (k)(1)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

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- Definition

Expected rate of compensation increases (for pay-related plans).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (k)(2)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

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- Definition

The interest rate used to adjust for the time value of money.

+ References

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- Definition

An assumption as to the rate of return on plan assets reflecting the average rate of earnings expected on the funds invested or to be invested to provide for the benefits included in the benefit obligation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Expected Long-Term Rate of Return on Plan Assets
-URI http://asc.fasb.org/extlink&oid=6512046

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (k)(3)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

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- Definition

Expected rate of compensation increases (for pay-related plans).

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (k)(2)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

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