Fair Value Measurements - Schedule of Financial Assets and Liabilities Measured at Fair Value (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Assets:
Total assets	$ 18,415	$ 13,424
Liabilities:
Contingent acquisition consideration	2,302	2,064
Total liabilities	2,302	2,064
Money Market Funds [Member]
Assets:
Cash equivalents	832	1,445
Commercial Paper [Member]
Assets:
Cash equivalents	8,998	5,649
Corporate Bonds [Member]
Assets:
Cash equivalents	8,585	6,330
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets:
Total assets	832	1,445
Liabilities:
Contingent acquisition consideration
Total liabilities
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Money Market Funds [Member]
Assets:
Cash equivalents	832	1,445
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Commercial Paper [Member]
Assets:
Cash equivalents
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Corporate Bonds [Member]
Assets:
Cash equivalents
Significant Other Observable Inputs (Level 2) [Member]
Assets:
Total assets	17,583	11,979
Liabilities:
Contingent acquisition consideration
Total liabilities
Significant Other Observable Inputs (Level 2) [Member] | Money Market Funds [Member]
Assets:
Cash equivalents
Significant Other Observable Inputs (Level 2) [Member] | Commercial Paper [Member]
Assets:
Cash equivalents	8,998	5,649
Significant Other Observable Inputs (Level 2) [Member] | Corporate Bonds [Member]
Assets:
Cash equivalents	8,585	6,330
Significant Unobservable Inputs (Level 3) [Member]
Assets:
Total assets
Liabilities:
Contingent acquisition consideration	2,302	2,064
Total liabilities	2,302	2,064
Significant Unobservable Inputs (Level 3) [Member] | Money Market Funds [Member]
Assets:
Cash equivalents
Significant Unobservable Inputs (Level 3) [Member] | Commercial Paper [Member]
Assets:
Cash equivalents
Significant Unobservable Inputs (Level 3) [Member] | Corporate Bonds [Member]
Assets:
Cash equivalents