Summary of Significant Accounting Policies - Schedule by Geographic Areas (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Revenue from External Customer [Line Items]
Revenue	$ 40,670,000	$ 33,797,000	$ 78,106,000	$ 66,485,000
United States [Member]
Revenue from External Customer [Line Items]
Revenue	26,695,000	21,887,000	51,483,000	43,084,000
United Kingdom [Member]
Revenue from External Customer [Line Items]
Revenue	3,643,000	3,087,000	7,105,000	6,095,000
International - All Other [Member]
Revenue from External Customer [Line Items]
Revenue	$ 10,332,000	$ 8,823,000	$ 19,518,000	$ 17,306,000