Summary of Restructuring Liability Activities (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Restructuring Cost and Reserve [Line Items]
Restructuring reserve, beginning balance	$ 2,318,000	$ 3,748,000	$ 1,329,000
Liabilities recognized	1,130,000	36,000	3,790,000
Utilized	(1,319,000)	(1,466,000)	(1,371,000)
Restructuring reserve, ending balance	2,129,000	2,318,000	3,748,000
Employee Separation Costs
Restructuring Cost and Reserve [Line Items]
Employee Separation, number of employees	14	2	30
Restructuring reserve, beginning balance	20,000	107,000	237,000
Liabilities recognized	803,000	26,000	195,000
Utilized	(219,000)	(113,000)	(325,000)
Restructuring reserve, ending balance	604,000	20,000	107,000
Contract Termination Costs
Restructuring Cost and Reserve [Line Items]
Restructuring reserve, beginning balance	2,298,000	3,641,000	1,092,000
Liabilities recognized	327,000	10,000	3,595,000
Utilized	(1,100,000)	(1,353,000)	(1,046,000)
Restructuring reserve, ending balance	$ 1,525,000	$ 2,298,000	$ 3,641,000