Acquisitions - Allocation of Purchase Price to Fair Value of Assets Acquired and Liabilities Assumed (Detail) - USD ($) $ in Millions	Sep. 30, 2017	Apr. 01, 2017	Dec. 31, 2016	Aug. 11, 2016
Business Acquisition [Line Items]
Goodwill	$ 1,097.0		$ 1,048.3
S&D Acquisition [Member]
Business Acquisition [Line Items]
Cash		$ 1.7	1.7
Accounts receivable		51.4	51.4
Inventories		62.5	62.5
Prepaid expenses and other assets		2.3	2.3
Property, plant & equipment		92.2	92.9
Goodwill		117.8	117.1
Intangible assets		119.0	119.0
Other assets		2.2	2.2
Accounts payable and accrued liabilities		(46.9)	(46.7)
Deferred tax liabilities		(43.1)	(43.3)
Other long-term liabilities		(5.5)	(5.5)
Total		353.6	353.6	$ 353.6
Eden Acquisition [Member]
Business Acquisition [Line Items]
Cash		19.6	19.6
Accounts receivable		94.4	95.4
Inventories		17.7	17.7
Prepaid expenses and other assets		6.2	6.2
Property, plant & equipment		98.9	107.1
Goodwill		299.8	299.7
Intangible assets		212.5	213.2
Other assets		2.8	2.8
Deferred tax assets		19.5	19.5
Current maturities of long-term debt		(2.7)	(2.7)
Accounts payable and accrued liabilities		(128.8)	(128.3)
Long-term debt		(3.1)	(3.1)
Deferred tax liabilities		(46.0)	(49.5)
Other long-term liabilities		(14.5)	(21.3)
Total		576.3	$ 576.3
Scenario, Adjustment [Member] | S&D Acquisition [Member]
Business Acquisition [Line Items]
Property, plant & equipment		(0.7)
Goodwill		0.7
Accounts payable and accrued liabilities		(0.2)
Deferred tax liabilities		0.2
Scenario, Adjustment [Member] | Eden Acquisition [Member]
Business Acquisition [Line Items]
Accounts receivable		(1.0)
Property, plant & equipment		(8.2)
Goodwill		0.1
Intangible assets		(0.7)
Accounts payable and accrued liabilities		(0.5)
Deferred tax liabilities		3.5
Other long-term liabilities		$ 6.8