Summary of Fair Value of Financial Assets and Liabilities Measured at Recurring Basis and Valuation Techniques (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012		Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, Total	$ 145,115		$ 131,596
Derivative liabilities	4,196		4,082
Market Approach Valuation Techniques | Money Market Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, Total	91,253		65,811
Market Approach Valuation Techniques | US Treasury Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, Total	10,999		6,921
Market Approach Valuation Techniques | U.S. Agency Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, Total	3,517		5,551
Market Approach Valuation Techniques | Corporate Notes/Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, Total	36,683		47,528
Market Approach Valuation Techniques | Certificates/Term Deposits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, Total	1,800		2,922
Market Approach Valuation Techniques | Derivative Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, Total	863	[1]	2,863	[1]
Market Approach Valuation Techniques | Derivative Financial Instruments, Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Derivative liabilities	2,012	[1]	300	[1]
Income Approach Valuation Techniques
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Contingent consideration	2,184		3,782
Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, Total	105,769		72,855
Fair Value, Inputs, Level 1 | Market Approach Valuation Techniques | Money Market Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, Total	91,253		65,811
Fair Value, Inputs, Level 1 | Market Approach Valuation Techniques | US Treasury Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, Total	10,999		3,499
Fair Value, Inputs, Level 1 | Market Approach Valuation Techniques | U.S. Agency Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, Total	3,517		3,545
Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, Total	39,346		58,741
Derivative liabilities	2,012		300
Fair Value, Inputs, Level 2 | Market Approach Valuation Techniques | US Treasury Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, Total			3,422
Fair Value, Inputs, Level 2 | Market Approach Valuation Techniques | U.S. Agency Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, Total			2,006
Fair Value, Inputs, Level 2 | Market Approach Valuation Techniques | Corporate Notes/Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, Total	36,683		47,528
Fair Value, Inputs, Level 2 | Market Approach Valuation Techniques | Certificates/Term Deposits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, Total	1,800		2,922
Fair Value, Inputs, Level 2 | Market Approach Valuation Techniques | Derivative Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Assets, Total	863	[1]	2,863	[1]
Fair Value, Inputs, Level 2 | Market Approach Valuation Techniques | Derivative Financial Instruments, Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Derivative liabilities	2,012	[1]	300	[1]
Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Derivative liabilities	2,184		3,782
Fair Value, Inputs, Level 3 | Income Approach Valuation Techniques
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Contingent consideration	$ 2,184		$ 3,782

[1] See Note 15 - Derivative Instruments for details.