Summary of Significant Accounting Policies - Summary of Weighted Average Assumptions Used to Calculate Fair Value of Option Awards (Parenthetical) (Detail) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Reverse stock split, description	1-for-5 reverse stock split
Reverse stock split ratio	5
Common stock dividends paid in cash	$ 0us-gaap_DividendsCommonStockCash	$ 0us-gaap_DividendsCommonStockCash	$ 0us-gaap_DividendsCommonStockCash

Name:	us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Amount of paid and unpaid common stock dividends declared with the form of settlement in cash.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.3-04)

-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

+ Details

Name:	us-gaap_DividendsCommonStockCash
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Ratio applied to the conversion of stock split, for example but not limited to, one share converted to two or two shares converted to one.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Stock Split

-URI http://asc.fasb.org/extlink&oid=6525746

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 4

-Subparagraph (SAB TOPIC 4.C)

-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187143-122770

+ Details

Name:	us-gaap_StockholdersEquityNoteStockSplitConversionRatio1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Description of the reverse stock split arrangement. Also provide the retroactive effect given by the reverse split that occurs after the balance sheet date but before the release of financial statements.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 4

-Subparagraph (SAB TOPIC 4.C)

-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187143-122770

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

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 4

-Section C

+ Details

Name:	us-gaap_StockholdersEquityReverseStockSplit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration