Business segment information - Operating Income (Loss) by GBU (Parenthetical) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Product Type Reporting Information [Line Items]
Charges related to U.S. Government resolutions	$ (82,500,000)	$ 88,463,000
Spine [Member]
Product Type Reporting Information [Line Items]
Charges related to U.S. Government resolutions		42,500,000
Orthopedics [Member]
Product Type Reporting Information [Line Items]
Charges related to U.S. Government resolutions		6,500,000
Corporate [Member]
Product Type Reporting Information [Line Items]
Charges related to U.S. Government resolutions		7,500,000
Senior management succession charges		$ 3,200,000