Supplemental Guarantor Information - Condensed Consolidating Statement of Operations and Comprehensive Income (Loss) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Condensed Financial Statements, Captions [Line Items]
Net sales	$ 711.4	$ 687.6	$ 2,224.6	$ 2,124.9
Cost of goods sold	467.6	451.1	1,444.9	1,391.1
Gross profit	243.8	236.5	779.7	733.8
Selling, general and administrative	116.3	116.8	399.0	386.2
Research and development	19.1	17.9	57.0	54.7
Operating income	108.4	101.8	323.7	292.9
Loss (earnings) from continuing operations of investment in subsidiaries	0.0	0.0	0.0	0.0
Other (income) expense:
Loss on sale of business	0.2	3.8	6.4	3.8
Loss on early extinguishment of debt	0.0	0.0	17.1	101.4
Net interest (income) expense	4.3	13.9	27.9	74.2
Other Income			(1.7)
Other expense	2.1	1.1		3.2
Income from continuing operations before income taxes	101.8	83.0	274.0	110.3
Provision for income taxes	10.6	34.1	46.5	52.1
Net income from continuing operations	91.2	48.9	227.5	58.2
Income from discontinued operations, net of tax	18.9	78.2	27.0	219.8
Gain from sale of discontinued operations, net of tax	0.0	(1.7)	0.0	198.9	$ (181.1)
(Loss) earnings from discontinued operations of investment in subsidiaries	0.0	0.0	0.0	0.0
Comprehensive income, net of tax
Net income	110.1	125.4	254.5	476.9
Changes in cumulative translation adjustment	(2.1)	34.5	23.1	502.8
Changes in market value of derivative financial instruments, net of tax	(1.0)	(3.0)	(0.7)	(2.3)
Comprehensive income	107.0	156.9	276.9	977.4
Parent Company Guarantor
Condensed Financial Statements, Captions [Line Items]
Net sales	0.0	0.0	0.0	0.0
Cost of goods sold	0.0	0.0	0.0	0.0
Gross profit	0.0	0.0	0.0	0.0
Selling, general and administrative	2.3	4.2	10.4	6.8
Research and development	0.0	0.0	0.0	0.0
Operating income	(2.3)	(4.2)	(10.4)	(6.8)
Loss (earnings) from continuing operations of investment in subsidiaries	(93.5)	(52.7)	(240.4)	(64.6)
Other (income) expense:
Loss on sale of business	0.0	0.0	0.0	0.0
Loss on early extinguishment of debt		0.0	0.0	0.0
Net interest (income) expense	0.0	0.0	0.0	0.0
Other Income			0.0
Other expense	0.0	0.0		0.0
Income from continuing operations before income taxes	91.2	48.5	230.0	57.8
Provision for income taxes	0.0	(0.4)	2.5	(0.4)
Net income from continuing operations	91.2	48.9	227.5	58.2
Income from discontinued operations, net of tax	0.0	0.0	0.0	0.0
Gain from sale of discontinued operations, net of tax		0.0		0.0
(Loss) earnings from discontinued operations of investment in subsidiaries	18.9	76.5	27.0	418.7
Comprehensive income, net of tax
Net income	110.1	125.4	254.5	476.9
Changes in cumulative translation adjustment	(2.1)	34.5	23.1	502.8
Changes in market value of derivative financial instruments, net of tax	(1.0)	(3.0)	(0.7)	(2.3)
Comprehensive income	107.0	156.9	276.9	977.4
Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net sales	0.0	0.0	0.0	0.0
Cost of goods sold	0.0	0.0	0.0	0.0
Gross profit	0.0	0.0	0.0	0.0
Selling, general and administrative	0.0	0.0	0.0	0.2
Research and development	0.0	0.0	0.0	0.0
Operating income	0.0	0.0	0.0	(0.2)
Loss (earnings) from continuing operations of investment in subsidiaries	(93.3)	(52.5)	(239.4)	(64.5)
Other (income) expense:
Loss on sale of business	0.0	0.0	0.0	0.0
Loss on early extinguishment of debt		0.0	0.0	0.0
Net interest (income) expense	(0.2)	(0.2)	(1.0)	(0.3)
Other Income			0.0
Other expense	0.0	0.0		0.0
Income from continuing operations before income taxes	93.5	52.7	240.4	64.6
Provision for income taxes	0.0	0.0	0.0	0.0
Net income from continuing operations	93.5	52.7	240.4	64.6
Income from discontinued operations, net of tax	0.0	0.0	0.0	0.0
Gain from sale of discontinued operations, net of tax		0.0		0.0
(Loss) earnings from discontinued operations of investment in subsidiaries	18.9	76.5	27.0	418.7
Comprehensive income, net of tax
Net income	112.4	129.2	267.4	483.3
Changes in cumulative translation adjustment	(2.1)	34.5	23.1	502.8
Changes in market value of derivative financial instruments, net of tax	(1.0)	(3.0)	(0.7)	(2.3)
Comprehensive income	109.3	160.7	289.8	983.8
Subsidiary Issuer
Condensed Financial Statements, Captions [Line Items]
Net sales	0.0	0.0	0.0	0.0
Cost of goods sold	0.0	0.0	0.0	0.0
Gross profit	0.0	0.0	0.0	0.0
Selling, general and administrative	0.2	0.0	0.7	0.3
Research and development	0.0	0.0	0.0	0.0
Operating income	(0.2)	0.0	(0.7)	(0.3)
Loss (earnings) from continuing operations of investment in subsidiaries	(69.5)	(37.1)	(278.9)	(215.9)
Other (income) expense:
Loss on sale of business	0.0	0.0	0.0	0.0
Loss on early extinguishment of debt		0.0	17.1	91.0
Net interest (income) expense	1.7	10.3	21.7	60.6
Other Income			0.0
Other expense	0.0	0.0		0.0
Income from continuing operations before income taxes	67.6	26.8	239.4	64.0
Provision for income taxes	0.0	0.0	0.0	0.0
Net income from continuing operations	67.6	26.8	239.4	64.0
Income from discontinued operations, net of tax	0.0	0.0	0.0	0.0
Gain from sale of discontinued operations, net of tax		0.0		0.0
(Loss) earnings from discontinued operations of investment in subsidiaries	18.9	76.5	27.0	418.7
Comprehensive income, net of tax
Net income	86.5	103.3	266.4	482.7
Changes in cumulative translation adjustment	(2.1)	34.5	23.1	502.8
Changes in market value of derivative financial instruments, net of tax	(1.0)	(3.0)	(0.7)	(2.3)
Comprehensive income	83.4	134.8	288.8	983.2
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net sales	711.4	687.6	2,224.6	2,124.9
Cost of goods sold	467.6	451.1	1,444.9	1,391.1
Gross profit	243.8	236.5	779.7	733.8
Selling, general and administrative	113.8	112.6	387.9	378.9
Research and development	19.1	17.9	57.0	54.7
Operating income	110.9	106.0	334.8	300.2
Loss (earnings) from continuing operations of investment in subsidiaries	0.0	0.0	0.0	0.0
Other (income) expense:
Loss on sale of business	0.2	3.8	6.4	3.8
Loss on early extinguishment of debt		0.0	0.0	10.4
Net interest (income) expense	2.8	3.8	7.2	13.9
Other Income			(1.7)
Other expense	2.1	1.1		3.2
Income from continuing operations before income taxes	105.8	97.3	322.9	268.9
Provision for income taxes	10.6	34.5	44.0	52.5
Net income from continuing operations	95.2	62.8	278.9	216.4
Income from discontinued operations, net of tax	18.9	78.2	27.0	219.8
Gain from sale of discontinued operations, net of tax		(1.7)		198.9
(Loss) earnings from discontinued operations of investment in subsidiaries	0.0	0.0	0.0	0.0
Comprehensive income, net of tax
Net income	114.1	139.3	305.9	635.1
Changes in cumulative translation adjustment	(2.1)	34.5	23.1	502.8
Changes in market value of derivative financial instruments, net of tax	(1.0)	(3.0)	(0.7)	(2.3)
Comprehensive income	111.0	170.8	328.3	1,135.6
Consolidation, Eliminations
Condensed Financial Statements, Captions [Line Items]
Net sales	0.0	0.0	0.0	0.0
Cost of goods sold	0.0	0.0	0.0	0.0
Gross profit	0.0	0.0	0.0	0.0
Selling, general and administrative	0.0	0.0	0.0	0.0
Research and development	0.0	0.0	0.0	0.0
Operating income	0.0	0.0	0.0	0.0
Loss (earnings) from continuing operations of investment in subsidiaries	256.3	142.3	758.7	345.0
Other (income) expense:
Loss on sale of business	0.0	0.0	0.0	0.0
Loss on early extinguishment of debt		0.0	0.0	0.0
Net interest (income) expense	0.0	0.0	0.0	0.0
Other Income			0.0
Other expense	0.0	0.0		0.0
Income from continuing operations before income taxes	(256.3)	(142.3)	(758.7)	(345.0)
Provision for income taxes	0.0	0.0	0.0	0.0
Net income from continuing operations	(256.3)	(142.3)	(758.7)	(345.0)
Income from discontinued operations, net of tax	0.0	0.0	0.0	0.0
Gain from sale of discontinued operations, net of tax		0.0		0.0
(Loss) earnings from discontinued operations of investment in subsidiaries	(56.7)	(229.5)	(81.0)	(1,256.1)
Comprehensive income, net of tax
Net income	(313.0)	(371.8)	(839.7)	(1,601.1)
Changes in cumulative translation adjustment	6.3	(103.5)	(69.3)	(1,508.4)
Changes in market value of derivative financial instruments, net of tax	3.0	9.0	2.1	6.9
Comprehensive income	$ (303.7)	$ (466.3)	$ (906.9)	$ (3,102.6)