Non-Marketable Investments - Additional Information (Detail) (USD $)	3 Months Ended	9 Months Ended				3 Months Ended	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013 Technology Related Private Equity Funds [Member]	Dec. 31, 2012 Technology Related Private Equity Funds [Member]	Sep. 30, 2012 Non-marketable Investments [Member]	Sep. 30, 2013 Non-marketable Investments [Member]	Sep. 30, 2012 Non-marketable Investments [Member]	Sep. 30, 2013 Maximum [Member] Participant	Sep. 30, 2013 Minimum [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Carrying value of the Company's non-marketable investments				$ 6,200,000	$ 6,600,000
Ownership interest of company										5.00%
Gain (losses) from non-marketable investments	0					800,000	(100,000)	900,000
Book value of investment	900,000	900,000	1,200,000
Bonus paid under cash bonus plan		$ 0
Cash bonus plan expiration date		Jun. 30, 2015
Participant in the cash bonus plan									10