Fair Value Measurements - Summary of Cash Equivalents, Marketable Securities and Long-Term Investments Measured at Fair Value (Detail) - USD ($) $ in Thousands | Jun. 30, 2015 | Dec. 31, 2014 |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | $ 20,872 | $ 25,884 |
Certificates of deposit [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 9,841 | 8,674 |
Money market funds [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 0 | 169 |
U.S. treasuries [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 4,041 | 5,557 |
Corporate bonds [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 2,010 | 2,020 |
Government-sponsored enterprise securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 3,000 | 7,493 |
Auction rate securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 1,980 | 1,971 |
Level 1 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 13,882 | 14,400 |
Level 1 [Member] | Certificates of deposit [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 9,841 | 8,674 |
Level 1 [Member] | Money market funds [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 0 | 169 |
Level 1 [Member] | U.S. treasuries [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 4,041 | 5,557 |
Level 1 [Member] | Corporate bonds [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 0 | 0 |
Level 1 [Member] | Government-sponsored enterprise securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 0 | 0 |
Level 1 [Member] | Auction rate securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 0 | 0 |
Level 2 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 5,010 | 9,513 |
Level 2 [Member] | Certificates of deposit [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 0 | 0 |
Level 2 [Member] | Money market funds [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 0 | 0 |
Level 2 [Member] | U.S. treasuries [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 0 | 0 |
Level 2 [Member] | Corporate bonds [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 2,010 | 2,020 |
Level 2 [Member] | Government-sponsored enterprise securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 3,000 | 7,493 |
Level 2 [Member] | Auction rate securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 0 | 0 |
Level 3 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 1,980 | 1,971 |
Level 3 [Member] | Certificates of deposit [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 0 | 0 |
Level 3 [Member] | Money market funds [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 0 | 0 |
Level 3 [Member] | U.S. treasuries [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 0 | 0 |
Level 3 [Member] | Corporate bonds [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 0 | 0 |
Level 3 [Member] | Government-sponsored enterprise securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | 0 | 0 |
Level 3 [Member] | Auction rate securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair Value | $ 1,980 | $ 1,971 |