Short-Term Marketable Securities - Summary of Short-Term Marketable Securities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 23,511	$ 11,538
Unrealized Gain	0	3
Unrealized Loss	12	0
Market Value	23,499	11,541
U.S. treasuries [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	5,558	1,500
Unrealized Gain	0	3
Unrealized Loss	1	0
Market Value	5,557	1,503
Government-sponsored enterprise securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	7,499	4,500
Unrealized Gain	0	0
Unrealized Loss	6	0
Market Value	7,493	4,500
Corporate bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	2,025	4,853
Unrealized Gain	0	0
Unrealized Loss	5	0
Market Value	2,020	4,853
Certificates of deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	8,429	685
Unrealized Gain	0	0
Unrealized Loss	0	0
Market Value	$ 8,429	$ 685

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

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (b)

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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

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-Publisher FASB

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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.

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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.

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