Summary of Changes in RSUs Outstanding (Parenthetical) (Detail)	9 Months Ended
Sep. 30, 2011 Year
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSUs granted, weighted-average remaining contractual term	1.2
Performance Based Awards \| Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted	300,000
Service Based Awards \| Non-Executive \| Target Amount
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted	400,000
Minimum \| Target Amount
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Actual number of RSUs that will ultimately be granted	0.00%
Maximum \| Target Amount
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Actual number of RSUs that will ultimately be granted	200.00%

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(2)(c)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 (c)(2)(iii)(1)

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

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
Namespace Prefix:	us-gaap
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration