Marketable Securities - Additional Information (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Equity [Line Items]
Fair value of investments owned	$ 45,000,000
Investments classified as available-for-sale, fair value	5,500,000
Marketable securities	45,002,000	0
NASDAQ OMX [Member]
Equity [Line Items]
Marketable securities	$ 39,500,000