Accrued Restructuring Costs - Additional Information (Detail) (USD $)	6 Months Ended		12 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2010
Restructuring Cost and Reserve [Line Items]
Severance and related benefit costs			$ 6,500,000
Restructuring costs		141,000
Facility Closing
Restructuring Cost and Reserve [Line Items]
Restructuring costs			$ 1,600,000
Lease expiration date	2013