Supplemental Guarantor Information - Condensed Consolidating Balance Sheet (Detail) - USD ($) $ in Millions	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 80.5		$ 74.3	$ 78.7		$ 86.3
Accounts and notes receivable, net	459.6		488.2
Inventories	396.7		387.5
Other current assets	104.7		89.4
Total current assets	1,041.5		1,039.4
Property, plant and equipment, net	280.3		272.6
Other assets
Investments in subsidiaries	0.0		0.0
Goodwill	2,287.5		2,072.7
Intangibles, net	354.2		276.3
Other non-current assets	206.5		145.5
Total other assets	2,848.2		2,494.5
Total assets	4,170.0		3,806.5
Current liabilities
Accounts payable	261.7		378.6
Employee compensation and benefits	68.7		111.7
Other current liabilities	379.8		328.4
Total current liabilities	710.2		818.7
Other liabilities
Long-term debt	1,215.1		787.6
Pension and other post-retirement compensation and benefits	89.2		90.0
Deferred tax liabilities	119.8		105.9
Other non-current liabilities	229.1		168.2
Total liabilities	2,363.4		1,970.4
Equity
Total equity	1,806.6	$ 1,870.4	1,836.1	1,888.9	$ 4,719.7	5,037.8
Total liabilities and equity	4,170.0		3,806.5
Parent Company Guarantor
Current assets
Cash and cash equivalents	0.3		0.1	0.1		0.0
Accounts and notes receivable, net	1.2		4.6
Inventories	0.0		0.0
Other current assets	2.9		3.4
Total current assets	4.4		8.1
Property, plant and equipment, net	0.0		0.0
Other assets
Investments in subsidiaries	1,969.2		1,903.8
Goodwill	0.0		0.0
Intangibles, net	0.0		0.0
Other non-current assets	22.3		23.3
Total other assets	1,991.5		1,927.1
Total assets	1,995.9		1,935.2
Current liabilities
Accounts payable	6.1		0.9
Employee compensation and benefits	0.2		0.2
Other current liabilities	33.7		47.6
Total current liabilities	40.0		48.7
Other liabilities
Long-term debt	128.8		29.9
Pension and other post-retirement compensation and benefits	0.0		0.0
Deferred tax liabilities	0.0		0.0
Other non-current liabilities	20.5		20.5
Total liabilities	189.3		99.1
Equity
Total equity	1,806.6		1,836.1
Total liabilities and equity	1,995.9		1,935.2
Guarantor Subsidiaries
Current assets
Cash and cash equivalents	0.0		0.0	0.0		0.0
Accounts and notes receivable, net	0.0		0.0
Inventories	0.0		0.0
Other current assets	0.0		0.0
Total current assets	0.0		0.0
Property, plant and equipment, net	0.0		0.0
Other assets
Investments in subsidiaries	1,968.7		2,036.1
Goodwill	0.0		0.0
Intangibles, net	0.0		0.0
Other non-current assets	1.0		0.0
Total other assets	1,969.7		2,036.1
Total assets	1,969.7		2,036.1
Current liabilities
Accounts payable	0.0		0.0
Employee compensation and benefits	0.0		0.0
Other current liabilities	0.5		1.5
Total current liabilities	0.5		1.5
Other liabilities
Long-term debt	0.0		130.8
Pension and other post-retirement compensation and benefits	0.0		0.0
Deferred tax liabilities	0.0		0.0
Other non-current liabilities	0.0		0.0
Total liabilities	0.5		132.3
Equity
Total equity	1,969.2		1,903.8
Total liabilities and equity	1,969.7		2,036.1
Subsidiary Issuer
Current assets
Cash and cash equivalents	0.1		0.1	3.2		0.0
Accounts and notes receivable, net	1.1		0.0
Inventories	0.0		0.0
Other current assets	0.1		2.2
Total current assets	1.3		2.3
Property, plant and equipment, net	0.0		0.0
Other assets
Investments in subsidiaries	2,719.8		2,675.7
Goodwill	0.0		0.0
Intangibles, net	0.0		0.0
Other non-current assets	1,591.5		696.1
Total other assets	4,311.3		3,371.8
Total assets	4,312.6		3,374.1
Current liabilities
Accounts payable	0.1		0.0
Employee compensation and benefits	0.0		0.0
Other current liabilities	7.7		4.4
Total current liabilities	7.8		4.4
Other liabilities
Long-term debt	2,336.3		1,333.9
Pension and other post-retirement compensation and benefits	0.0		0.0
Deferred tax liabilities	0.0		0.0
Other non-current liabilities	0.0		0.0
Total liabilities	2,344.1		1,338.3
Equity
Total equity	1,968.5		2,035.8
Total liabilities and equity	4,312.6		3,374.1
Non-Guarantor Subsidiaries
Current assets
Cash and cash equivalents	80.1		74.1	75.4		86.3
Accounts and notes receivable, net	458.9		483.6
Inventories	396.7		387.5
Other current assets	101.7		99.2
Total current assets	1,037.4		1,044.4
Property, plant and equipment, net	280.3		272.6
Other assets
Investments in subsidiaries	0.0		0.0
Goodwill	2,287.5		2,072.7
Intangibles, net	354.2		276.3
Other non-current assets	184.2		729.7
Total other assets	2,825.9		3,078.7
Total assets	4,143.6		4,395.7
Current liabilities
Accounts payable	257.1		377.7
Employee compensation and benefits	68.5		111.5
Other current liabilities	337.9		290.3
Total current liabilities	663.5		779.5
Other liabilities
Long-term debt	342.5		596.6
Pension and other post-retirement compensation and benefits	89.2		90.0
Deferred tax liabilities	119.8		105.9
Other non-current liabilities	208.6		147.7
Total liabilities	1,423.6		1,719.7
Equity
Total equity	2,720.0		2,676.0
Total liabilities and equity	4,143.6		4,395.7
Consolidation, Eliminations
Current assets
Cash and cash equivalents	0.0		0.0	$ 0.0		$ 0.0
Accounts and notes receivable, net	(1.6)		0.0
Inventories	0.0		0.0
Other current assets	0.0		(15.4)
Total current assets	(1.6)		(15.4)
Property, plant and equipment, net	0.0		0.0
Other assets
Investments in subsidiaries	(6,657.7)		(6,615.6)
Goodwill	0.0		0.0
Intangibles, net	0.0		0.0
Other non-current assets	(1,592.5)		(1,303.6)
Total other assets	(8,250.2)		(7,919.2)
Total assets	(8,251.8)		(7,934.6)
Current liabilities
Accounts payable	(1.6)		0.0
Employee compensation and benefits	0.0		0.0
Other current liabilities	0.0		(15.4)
Total current liabilities	(1.6)		(15.4)
Other liabilities
Long-term debt	(1,592.5)		(1,303.6)
Pension and other post-retirement compensation and benefits	0.0		0.0
Deferred tax liabilities	0.0		0.0
Other non-current liabilities	0.0		0.0
Total liabilities	(1,594.1)		(1,319.0)
Equity
Total equity	(6,657.7)		(6,615.6)
Total liabilities and equity	$ (8,251.8)		$ (7,934.6)