Fair Value Measurements - Summary of Fair Value of Financial Assets and Liabilities that are Measured at Fair Value and the Classification by Level of Input within Fair Value Hierarchy (Detail) (USD $) | Mar. 31, 2014 | Dec. 31, 2013 |
In Thousands, unless otherwise specified |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total cash and cash equivalents | $35,843 | $69,649 |
Total Investments | 29,268 | ' |
Total cash, cash equivalents, and investments | 65,111 | ' |
Certificates Of Deposit (Due Within 1 Year) [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total Investments | 9,899 | ' |
Commercial Paper (Due Within 1 Year) [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total Investments | 2,997 | ' |
Corporate Bonds (Due Within 1 Year) [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total Investments | 13,867 | ' |
Government Agencies (Due Within 1 Year) [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total Investments | 2,505 | ' |
Cash and Money Market Accounts [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total cash and cash equivalents | 30,451 | 69,649 |
Certificates of Deposit [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total cash and cash equivalents | 1,680 | ' |
Commercial Paper [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total cash and cash equivalents | 1,000 | ' |
Corporate Bonds [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total cash and cash equivalents | 2,712 | ' |
Level 1 [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total cash and cash equivalents | 30,451 | 69,649 |
Total Investments | ' | ' |
Total cash, cash equivalents, and investments | 30,451 | ' |
Level 1 [Member] | Certificates Of Deposit (Due Within 1 Year) [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total Investments | ' | ' |
Level 1 [Member] | Commercial Paper (Due Within 1 Year) [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total Investments | ' | ' |
Level 1 [Member] | Corporate Bonds (Due Within 1 Year) [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total Investments | ' | ' |
Level 1 [Member] | Government Agencies (Due Within 1 Year) [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total Investments | ' | ' |
Level 1 [Member] | Cash and Money Market Accounts [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total cash and cash equivalents | 30,451 | 69,649 |
Level 1 [Member] | Certificates of Deposit [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total cash and cash equivalents | ' | ' |
Level 1 [Member] | Commercial Paper [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total cash and cash equivalents | ' | ' |
Level 1 [Member] | Corporate Bonds [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total cash and cash equivalents | ' | ' |
Level 2 [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total cash and cash equivalents | 5,392 | ' |
Total Investments | 29,268 | ' |
Total cash, cash equivalents, and investments | 34,660 | ' |
Level 2 [Member] | Certificates Of Deposit (Due Within 1 Year) [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total Investments | 9,899 | ' |
Level 2 [Member] | Commercial Paper (Due Within 1 Year) [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total Investments | 2,997 | ' |
Level 2 [Member] | Corporate Bonds (Due Within 1 Year) [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total Investments | 13,867 | ' |
Level 2 [Member] | Government Agencies (Due Within 1 Year) [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total Investments | 2,505 | ' |
Level 2 [Member] | Cash and Money Market Accounts [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total cash and cash equivalents | ' | ' |
Level 2 [Member] | Certificates of Deposit [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total cash and cash equivalents | 1,680 | ' |
Level 2 [Member] | Commercial Paper [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total cash and cash equivalents | 1,000 | ' |
Level 2 [Member] | Corporate Bonds [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total cash and cash equivalents | 2,712 | ' |
Level 3 [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total cash and cash equivalents | ' | ' |
Total Investments | ' | ' |
Total cash, cash equivalents, and investments | ' | ' |
Level 3 [Member] | Certificates Of Deposit (Due Within 1 Year) [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total Investments | ' | ' |
Level 3 [Member] | Commercial Paper (Due Within 1 Year) [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total Investments | ' | ' |
Level 3 [Member] | Corporate Bonds (Due Within 1 Year) [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total Investments | ' | ' |
Level 3 [Member] | Government Agencies (Due Within 1 Year) [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total Investments | ' | ' |
Level 3 [Member] | Cash and Money Market Accounts [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total cash and cash equivalents | ' | ' |
Level 3 [Member] | Certificates of Deposit [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total cash and cash equivalents | ' | ' |
Level 3 [Member] | Commercial Paper [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total cash and cash equivalents | ' | ' |
Level 3 [Member] | Corporate Bonds [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total cash and cash equivalents | ' | ' |