Long-Term Investments - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Investments Schedule [Abstract]
Auction rate securities held, at par value	$ 2,500,000
Maturity of long-term investment	2038
Recognized cumulative losses	500,000
Unrealized (losses) gains on auction rate securities	(9,000)	(200,000)	100,000
Cumulative unrealized gains	200,000
Carrying value of auction rate security	$ 2,000,000