Cash and Cash Equivalents, Restricted Cash and Short-Term Investments - Summary of Cash, Cash Equivalents and Restricted Cash (Detail) - USD ($)	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash and Cash Equivalents [Abstract]
Cash	$ 1,666,000	$ 1,511,000
Money market	36,783,000	33,255,000
Total cash and cash equivalents	38,449,000	34,766,000	$ 10,014,000	$ 8,896,000
Restricted cash	0	250,000
Total	$ 38,449,000	$ 35,016,000