Business Combinations - Summary of Fair Values of Assets Acquired and Liabilities Assumed (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Jul. 13, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Goodwill	$ 10,668.4	$ 10,643.9		$ 9,934.2
In Process Research and Development (IPR&D) [Member]
Business Acquisition [Line Items]
Intangible assets not subject to amortization	$ 209.0
LDR Holding Corporation [Member]
Business Acquisition [Line Items]
Cash			$ 92.8
Accounts receivable, net			30.5
Inventory			97.0
Other current assets			5.6
Property, plant and equipment			24.7
Other assets			73.8
Goodwill			507.2
Total assets acquired			1,476.6
Current liabilities			122.5
Long-term debt			0.5
Deferred taxes			236.7
Other long-term liabilities			3.0
Total liabilities assumed			362.7
Net assets acquired			1,113.9
LDR Holding Corporation [Member] | Trademarks and Trade Names [Member]
Business Acquisition [Line Items]
Intangible assets subject to amortization			74.0
LDR Holding Corporation [Member] | In Process Research and Development (IPR&D) [Member]
Business Acquisition [Line Items]
Intangible assets not subject to amortization			2.0
LDR Holding Corporation [Member] | Technology [Member]
Business Acquisition [Line Items]
Intangible assets subject to amortization			447.0
LDR Holding Corporation [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Intangible assets subject to amortization			$ 122.0