Postretirement Benefit Plans - Changes in Projected Benefit Obligations of Pension and Other Employee-Related Defined Benefit Plans (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Change in benefit obligation
Benefit obligation – January 1	$ 531.0	$ 561.3
Service cost	6.8	6.3
Interest cost	16.5	18.3
Amendments	2.0	0.4
Actuarial loss (gain)	20.7	8.2
Benefits and expenses paid	(33.6)	(32.7)
Acquired	3.5	0.0
Settlement	(0.4)	(28.5)
Curtailment	0.0	(0.2)
Foreign currency translation	10.6	(2.1)
Benefit obligation – December 31	557.1	531.0	$ 561.3
Other Postretirement Benefits Plan [Member]
Change in benefit obligation
Benefit obligation – January 1	138.8	143.4
Service cost	0.8	0.9	0.9
Interest cost	4.4	4.9	5.0
Amendments	0.4	0.0
Actuarial loss (gain)	1.9	(1.9)
Benefits and expenses paid	(8.2)	(8.5)
Acquired	0.0	0.0
Settlement	0.0	0.0
Curtailment	0.0	0.0
Foreign currency translation	0.0	0.0
Benefit obligation – December 31	138.1	138.8	143.4
Pension Plan [Member]
Change in benefit obligation
Benefit obligation – January 1	392.2
Service cost	6.0	5.4	5.0
Interest cost	12.1	13.4	14.5
Settlement		(1.4)
Benefit obligation – December 31	419.0	392.2
U.S. Plan [Member]
Change in benefit obligation
Settlement		(26.6)
U.S. Plan [Member] \| Pension Plan [Member]
Change in benefit obligation
Benefit obligation – January 1	312.3	339.9
Service cost	4.6	4.1	3.5
Interest cost	10.5	11.9	13.0
Amendments	1.6	0.0
Actuarial loss (gain)	19.1	5.9
Benefits and expenses paid	(22.4)	(21.5)
Acquired	0.0	0.0
Settlement	0.0	(28.0)
Curtailment	0.0	0.0
Foreign currency translation	0.0	0.0
Benefit obligation – December 31	325.7	312.3	339.9
International Plan [Member] \| Pension Plan [Member]
Change in benefit obligation
Benefit obligation – January 1	79.9	78.0
Service cost	1.4	1.3	1.5
Interest cost	1.6	1.5	1.5
Amendments	0.0	0.4
Actuarial loss (gain)	(0.3)	4.2
Benefits and expenses paid	(3.0)	(2.7)
Acquired	3.5	0.0
Settlement	(0.4)	(0.5)
Curtailment	0.0	(0.2)
Foreign currency translation	10.6	(2.1)
Benefit obligation – December 31	$ 93.3	$ 79.9	$ 78.0

Defined Benefit Plan Benefits And Expenses Paid, Including Unfunded Portion

No definition available.

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- Definition

Amount of gain (loss) from change in actuarial assumptions which (increases) decreases benefit obligation of defined benefit plan. Assumptions include, but are not limited to, interest, mortality, employee turnover, salary, and temporary deviation from substantive plan.

+ References

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- Definition

Amount of actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

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- Definition

Amount of increase in benefit obligation of defined benefit plan from business combination.

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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- Definition

Amount of (increase) decrease in benefit obligation of defined benefit plan from event reducing expected years of future service of present employees or eliminating accrual of benefits for some or all future services of present employees.

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Amount of foreign currency translation gain (loss) which (increases) decreases benefit obligation of defined benefit plan.

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- Definition

Amount of cost recognized for passage of time related to defined benefit plan.

+ 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 (h)(2)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

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- Definition

Amount of increase (decrease) in benefit obligation of defined benefit plan from change in terms of existing plan or initiation of new plan.

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- Definition

Amount of cost for actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

+ 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 (h)(1)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

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- Definition

Amount of (increase) decrease to benefit obligation of defined benefit plan from irrevocable action relieving primary responsibility for benefit obligation and eliminating risk for obligation and assets used to effect settlement. Includes, but is not limited to, lump-sum cash payment to participant in exchange for right to receive specified benefits, purchase of nonparticipating annuity contract and change from remeasurement.

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