Cash, Cash Equivalents, and Investments - Summary of Amortized Cost and Fair Value of Short-term and Long-term Investments (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Due in less than one year	$ 17,700	$ 9,101
Due after one year, through two years	14,674	12,023
Amortized Cost [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Due in less than one year	17,700
Due after one year, through two years	14,674
Total short-term and long-term investments	32,374
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Due in less than one year	17,706
Due after one year, through two years	14,677
Total short-term and long-term investments	$ 32,383