Retirement Benefit Plans - Asset Allocations (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Discretionary contributions to German plans	$ 30.2	$ 137.5
U.S. Plans:
Defined Benefit Plan, Assets for Plan Benefits [Abstract]
Asset allocations	100.00%	100.00%
Non-U.S. Plans:
Defined Benefit Plan, Assets for Plan Benefits [Abstract]
Asset allocations	100.00%	100.00%
Cash and Cash Equivalents [Member] \| U.S. Plans:
Defined Benefit Plan, Assets for Plan Benefits [Abstract]
Asset allocations	10.00%	9.00%
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Target allocation, range minimum	5.00%
Target allocation, range maximum	15.00%
Cash and Cash Equivalents [Member] \| Non-U.S. Plans:
Defined Benefit Plan, Assets for Plan Benefits [Abstract]
Asset allocations	3.00%	4.00%
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Target allocation, range minimum	0.00%
Target allocation, range maximum	7.00%
Fixed Income Funds [Member] \| U.S. Plans:
Defined Benefit Plan, Assets for Plan Benefits [Abstract]
Asset allocations	55.00%	54.00%
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Target allocation, range minimum	45.00%
Target allocation, range maximum	65.00%
Fixed Income Funds [Member] \| Non-U.S. Plans:
Defined Benefit Plan, Assets for Plan Benefits [Abstract]
Asset allocations	47.00%	42.00%
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Target allocation, range minimum	43.00%
Target allocation, range maximum	53.00%
Equity Securities [Member] \| U.S. Plans:
Defined Benefit Plan, Assets for Plan Benefits [Abstract]
Asset allocations	35.00%	37.00%
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Target allocation, range minimum	25.00%
Target allocation, range maximum	45.00%
Equity Securities [Member] \| Non-U.S. Plans:
Defined Benefit Plan, Assets for Plan Benefits [Abstract]
Asset allocations	50.00%	54.00%
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Target allocation, range minimum	45.00%
Target allocation, range maximum	56.00%

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Target allocation maximum percentage of investments of this type to total plan assets presented on a weighted average basis.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

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-Subparagraph (d)(i)

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Target allocation minimum percentage of investments of this type to total plan assets presented on a weighted average basis.

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Percentage of fair value of investments (categorized by debt securities, equity securities, real estate and other plan assets) to the fair value of plan assets held.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 5

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e2446-114920

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Amount of discretionary contributions made by an employer to a defined contribution plan.

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