Long-Term Investments - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Investments Schedule [Abstract]
Auction rate securities held, at par value	$ 2.5
Maturity of long-term investment	2038
Recognized cumulative losses	0.5
Unrealized (losses) gains on auction rate securities	(0.2)	0.1	0.3
Cumulative unrealized gains	0.2
Carrying value of auction rate security	$ 2.0