Marketable Investments - Summary of Company's Marketable Investments (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 63,151
Gross Unrealized Gains	20
Gross Unrealized Losses	(67)
Market Value	63,104
Federal Agency Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,801
Gross Unrealized Losses	(1)
Market Value	1,800
Corporate Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	61,350	$ 47,939
Gross Unrealized Gains	20
Gross Unrealized Losses	(66)	(164)
Market Value	$ 61,304	$ 47,775

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale.

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-Publisher FASB
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Amount of debt securities categorized neither as held-to-maturity nor trading.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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