Fair Value of Assets and Liabilities Measured on Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	$ 206,979	$ 182,530
Short-term investments	452	576
Contingent consideration	(6,436)	(9,571)
Deferred compensation	(1,394)	(2,073)
Foreign currency future	(240)
Quoted Prices in Active Markets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	206,979	181,198
Short-term investments	0	0
Contingent consideration	0	0
Deferred compensation	0	0
Foreign currency future	0
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	1,332
Short-term investments	452	576
Contingent consideration	0	0
Deferred compensation	0	0
Foreign currency future	(240)
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Short-term investments	0	0
Contingent consideration	(6,436)	(9,571)
Deferred compensation	(1,394)	(2,073)
Foreign currency future	$ 0