Preferred and Common Stock - Schedule of Share-Based Compensation (Detail)	12 Months Ended
Dec. 31, 2012
2002 and Prior [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting	1 year
Term	10 years
Reload feature	One reload over option term
2003 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting	3 years
Term	10 years
Reload feature	One reload in 2004 for 1/3 vesting in 2004
2004 - 2009 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting	3 years
Term	6 years
Reload feature	None
2010 And Forward [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting	3 years
Term	10 years
Reload feature	None

Estimated period over which an employee is required to provide service in exchange for the equity-based payment award, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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- Definition

Description of significant modifications (such as a change in expiration dating, vesting rights, or exercise prices) to an equity-based compensation plan, including the terms of the modifications.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph g(2)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (h)(2)(i)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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