Marketable Investments - Summary of Maturity Periods of the Marketable Securities (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
FY 2016	$ 3,000
FY 2017	37,220
FY 2018	22,884
Total	63,104
Federal Agency Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
FY 2018	1,800
Total	1,800
Corporate Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
FY 2016	3,000
FY 2017	37,220
FY 2018	21,084
Total	$ 61,304	$ 47,775