Commitments and Contingencies - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
Sep. 30, 2014
Long Term Purchase Commitment [Line Items]
Unconditional purchase obligations, term	4 years
Unconditional purchase obligations	$ 48,763
Amount outstanding under letters of credit	$ 1,278
Minimum
Long Term Purchase Commitment [Line Items]
Unconditional purchase obligations, term	1 year
Maximum
Long Term Purchase Commitment [Line Items]
Unconditional purchase obligations, term	4 years

Amount of the unrecorded obligation to transfer funds in the future for fixed or minimum amounts or quantities of goods or services at fixed or minimum prices (for example, as in take-or-pay contracts or throughput contracts).

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 440

-SubTopic 10

-Section 50

-Paragraph 4

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6394976&loc=d3e25336-109308

Name:	us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant