Fair Value Measurement - Summary of Restricted Certificates of Deposit (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Cost	$ 5,903	$ 9,870
Recorded Basis	7,108	16,748
Current Available-for-Sale [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Cost	7,121	16,728
Recorded Basis	7,108	16,748
Current Available-for-Sale [Member] \| Restricted certificates of deposit [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Cost	63,944	0
Gross Unrealized Gains	0	0
Recorded Basis	$ 63,944	$ 0
Fair Value Category		2

Amount of investments in debt and equity securities, including, but not limited to, held-to-maturity, trading and available-for-sale expected to be converted to cash, sold or exchanged within one year or the normal operating cycle, if longer.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.2)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6871852&loc=d3e26626-111562

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 2

-Article 5

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section 45

-Paragraph 1

-Subparagraph (f)

-URI http://asc.fasb.org/extlink&oid=28358313&loc=d3e6676-107765

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