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	Dec. 31, 2013	Dec. 31, 2012
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Due in less than one year	$ 9,101	$ 1,681
Due after one year, through two years	12,023
Amortized Cost [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Due in less than one year	9,101
Due after one year, through two years	12,023
Total short-term and long-term investments	21,124
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Due in less than one year	9,103
Due after one year, through two years	12,022
Total short-term and long-term investments	$ 21,125