Post Employment Plans - Accumulated benefit obligation and projected benefit obligation in excess of plan assets (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Postemployment Benefits [Abstract]
Unfunded accumulated projected benefit obligation	$ 207.5	$ 180.8
Accumulated benefit obligation	107.4	93.7
Fair value of plan assets	71.1	62.1
Projected benefit obligation	114.2	99.4
Fair value of plan assets	$ 71.1	$ 62.1

Amount of actuarial present value of benefits attributed to employee service rendered, excluding assumptions about future compensation level.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

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- Definition

Amount of plan asset for defined benefit pension plan with projected benefit obligation in excess of plan assets.

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Amount of projected benefit obligation for defined benefit pension plan with projected benefit obligation in excess of plan assets.

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Amount of accumulated benefit obligation for defined benefit plan with accumulated benefit obligation in excess of plan assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e2417-114920

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-Publisher FASB
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-Publisher FASB
-Name Accounting Standards Codification
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Amount of plan asset for defined benefit plan with accumulated benefit obligation in excess of plan assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e2417-114920

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