Restructuring Impairments and Other Costs - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 3,100,000	$ 5,800,000
Selling, general and administrative expenses	936,847,000	738,901,000	718,230,000
Settlements of legal matters and an impairment of an intangible asset	32,700,000	5,200,000
Settlements of legal matters and impairment of long-term assets	12,600,000	3,700,000
Restructuring Orthodontic Plan
Restructuring Cost and Reserve [Line Items]
Restructuring costs	1,700,000
Selling, general and administrative expenses	3,300,000
Other Restructuring
Restructuring Cost and Reserve [Line Items]
Restructuring costs	1,900,000
Restructuring Prior Year Plans - 2010 and 2009
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve, Accrual Adjustment	$ 500,000