Restructuring and Other Special Charges and Related Liability Balances (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013
Restructuring January 2012 Plan
Restructuring Cost and Reserve [Line Items]
Accrual at December 31, 2012	$ 5,178
Cash Payments	(2,115)
Accrual at September 30, 2013	3,063
Restructuring January 2012 Plan | Workforce reduction
Restructuring Cost and Reserve [Line Items]
Accrual at December 31, 2012	1,191
Cash Payments	(460)
Accrual at September 30, 2013	731
Restructuring January 2012 Plan | Consolidation of office facilities
Restructuring Cost and Reserve [Line Items]
Accrual at December 31, 2012	3,938
Cash Payments	(1,629)
Accrual at September 30, 2013	2,309
Restructuring January 2012 Plan | Other costs and professional fees
Restructuring Cost and Reserve [Line Items]
Accrual at December 31, 2012	49
Cash Payments	(26)
Accrual at September 30, 2013	23
Restructuring November 2012 Plan
Restructuring Cost and Reserve [Line Items]
Accrual at December 31, 2012	11,985
Expense	19,995
Cash Payments	(20,127)
Non-Cash Utilization	(5,315)
Accrual at September 30, 2013	6,538
Restructuring November 2012 Plan | Workforce reduction
Restructuring Cost and Reserve [Line Items]
Accrual at December 31, 2012	11,902
Expense	9,645
Cash Payments	(17,838)
Non-Cash Utilization	(1,821)
Accrual at September 30, 2013	1,888
Restructuring November 2012 Plan | Consolidation of office facilities
Restructuring Cost and Reserve [Line Items]
Expense	6,028
Cash Payments	(1,569)
Accrual at September 30, 2013	4,459
Restructuring November 2012 Plan | Impairment of Assets
Restructuring Cost and Reserve [Line Items]
Expense	3,494
Non-Cash Utilization	(3,494)
Restructuring November 2012 Plan | Other costs and professional fees
Restructuring Cost and Reserve [Line Items]
Accrual at December 31, 2012	83
Expense	828
Cash Payments	(720)
Accrual at September 30, 2013	$ 191