Accrued Restructuring Costs - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Restructuring Cost and Reserve [Line Items]
Severance and related benefit costs			$ 6,500,000
Restructuring costs		(62,000)	8,064,000
Facility Closing
Restructuring Cost and Reserve [Line Items]
Restructuring costs		$ (62,000)	$ 1,563,000
Lease expiration date	2013