Fair Value Measurement - Company's Fair Value Hierarchy for its Financial Assets and Liabilities (Detail) (Fair Value, Measurements, Recurring [Member], USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Financial assets:
Total financial assets	$ 4,084	$ 4,084
Money Market Investment [Member]
Financial assets:
Total financial assets	4,084	4,084
Quoted Prices in Active Markets for Identical Items (Level 1) [Member]
Financial assets:
Total financial assets	4,084	4,084
Quoted Prices in Active Markets for Identical Items (Level 1) [Member] | Money Market Investment [Member]
Financial assets:
Total financial assets	4,084	4,084
Significant Other Observable Inputs (Level 2) [Member]
Financial assets:
Total financial assets
Significant Other Observable Inputs (Level 2) [Member] | Money Market Investment [Member]
Financial assets:
Total financial assets
Significant Unobservable Inputs (Level 3) [Member]
Financial assets:
Total financial assets
Significant Unobservable Inputs (Level 3) [Member] | Money Market Investment [Member]
Financial assets:
Total financial assets