Summary of Significant Accounting Policies - Schedule of Available-for-Sale Securities in an Unrealized Loss Position (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Aggregate Fair Value	$ 37,581
Unrealized Losses	(9)
Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Aggregate Fair Value	7,098
Unrealized Losses	(1)
Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Aggregate Fair Value	30,483
Unrealized Losses	$ (8)

This item represents the aggregate fair value of investments in debt and equity securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for less than twelve months.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 7

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27337-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 6

-Subparagraph (a)(1)

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

Name:	us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant