Restructuring and Other Impairment Charges - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2012 2012 Restructuring Charges Facility	Dec. 31, 2012 LMA Restructuring Program	Dec. 31, 2012 LMA Restructuring Program Employee termination cost	Dec. 31, 2012 LMA Restructuring Program Facility Closure Costs	Dec. 31, 2012 LMA Restructuring Program Contract Termination Costs	Dec. 31, 2011 2011 Restructuring Program Facility	Dec. 31, 2011 2011 Restructuring Program Contract Termination Costs
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges		$ 3,700,000	$ 16,000,000	$ 5,000,000	$ 10,000,000	$ 1,000,000		$ 2,700,000
Number of facilities under restructuring program		3					3
Restructuring charges		2,400,000	2,515,000				3,047,000
Contract termination costs			274,000				2,600,000
Percentage of premises eliminated							50.00%
Termination benefits			2,229,000				400,000
Impairment charges	$ 2,500,000