Cash Cash Equivalents and Marketable Securities - Additional Information (Detail) (USD $)	6 Months Ended	12 Months Ended
	Jun. 30, 2014 Investment	Dec. 31, 2013
Cash, cash equivalents and marketable securities [Line Items]
Long-term marketable securities, minimum original maturity term	1 year
Marketable securities, average remaining contractual maturity period	10 months 9 days
Number of debt securities in unrealized loss positions	22
Debt securities in unrealized loss positions, total unrealized loss	$ 3,957	$ 9,936
Debt securities in unrealized loss positions, total fair market value	8,742,000
Credit risk	0
Gain (loss) on investments	0	0
Debt Securities
Cash, cash equivalents and marketable securities [Line Items]
Debt securities in unrealized loss positions, total unrealized loss	$ 4,000
Minimum
Cash, cash equivalents and marketable securities [Line Items]
Marketable securities, minimum original maturity term	90 days