Basis of Presentation and Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Millions		3 Months Ended				9 Months Ended		12 Months Ended
	Jan. 01, 2018	Sep. 30, 2018	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Basis of Presentation and Significant Accounting Policies [Line Items]
Net cash used in operating activities						$ 181.6	$ (23.8)
Net cash used in financing activities						(1,768.0)	(1,005.9)
Customer Supply Chain [Member]
Basis of Presentation and Significant Accounting Policies [Line Items]
Cost of products sold			$ 12.9	$ 15.9	$ 1.8		30.6	$ 40.1
Customer Supply Chain [Member] | Discontinued Operations [Member]
Basis of Presentation and Significant Accounting Policies [Line Items]
Cost of products sold			1.7	$ 1.6	$ 1.3		4.6	$ 7.3
ASU 2017-07 [Member]
Basis of Presentation and Significant Accounting Policies [Line Items]
Income reclassified from selling, general and administrative expenses ("SG&A") to other expense (income), net			2.4				7.4
Accounting Standards Update 2016-15 [Member]
Basis of Presentation and Significant Accounting Policies [Line Items]
Net cash used in operating activities							(34.2)
Net cash used in financing activities							34.2
Accounting Standards Update 2016-16 [Member] | Retained Earnings And Prepaid Expenses And Other [Member]
Basis of Presentation and Significant Accounting Policies [Line Items]
Retained earnings and prepaid expenses	$ 17.8
Sprue Aegis [Member]
Basis of Presentation and Significant Accounting Policies [Line Items]
Revenue from related parties		$ 0.0	$ 8.6			$ 7.5	$ 24.0
Investment owned, percentage		23.40%				23.40%