Schedule of Company Financial Assets and Liabilities at Fair Value on Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Money market investments	$ 21,094	$ 27,871
Available for sale securities	4,513	3,255
Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Money market investments	21,094	27,871
Available for sale securities	4,513	3,255
Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Money market investments	0	0
Available for sale securities	0	0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Money market investments	0	0
Available for sale securities	$ 0	$ 0