Restructuring - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2009 Person	Dec. 31, 2011 2011 Restructuring Program	Apr. 11, 2011 2011 Restructuring Program Person
Restructuring Cost and Reserve [Line Items]
Number of senior management members entered into separation agreements			4
Restructuring costs incurred		$ 10.9
Number of senior executives included in restructuring expense related to severance benefits	3