Balance Sheet Details - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Realized gains (losses) recognized in interest and other income	$ 0	$ 0	$ 0
Depreciation and amortization expense on equipment and improvements	2,900,000	4,000,000	4,400,000
Impairment charge related to restructuring against certain equipment and improvements		$ 1,000,000