Marketable Investments - Summary of Company's Marketable Investments (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Market Value	$ 60,832	$ 54,885
Corporate Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	60,792	55,005
Gross Unrealized Gains	56	13
Gross Unrealized Losses	(16)	(133)
Market Value	$ 60,832	$ 54,885

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

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-Publisher FASB

-Name Accounting Standards Codification

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-SubTopic 10

-Section 50

-Paragraph 2

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

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

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This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

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Amount of investment in debt and equity securities categorized neither as trading securities nor held-to-maturity securities and intended be sold or mature one year or operating cycle, if longer.

+ References

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

-Publisher FASB

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