Fair Value Measurements and Investments in Marketable Securities - Additional Information (Detail) - Jun. 30, 2015 $ in Millions	USD ($) Security
Fair Value Disclosures [Abstract]
Aggregate fair value of securities held by the Company in an unrealized loss position \| $	$ 64.2
Number of securities in unrealized loss positions	50

Number of investment positions in available-for-sale investments in a continuous unrealized loss position for which an other-than-temporary impairment (OTTI) has not been recognized in the income statement.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 6

-Subparagraph (b)(3)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant