Target allocation percentage of investments in debt securities to total plan assets presented on a weighted-average basis as of the measurement date of the latest statement of financial position.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 5

-Subparagraph d(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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 715

-SubTopic 20

-Section 50

-Paragraph 5

-Subparagraph (c)(i)

-URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e2446-114920

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (d)(i)

-URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e1928-114920

Name:	us-gaap_DefinedBenefitPlanTargetAllocationPercentageOfAssetsDebtSecurities
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Weighted Average Target Asset Allocations (Detail) (Pension Plans, Defined Benefit)			12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011 US Large Capitalization Equities	Dec. 31, 2011 US Small Capitalization Equities	Dec. 31, 2011 International Equities	Dec. 31, 2011 US Long-Duration Fixed Income	Dec. 31, 2011 High Yield Fixed Income
Schedule of Net Periodic Benefit Costs Weighted Average Assumptions [Line Items]
Weighted average target asset allocation - equity securities			17.00%	4.00%	4.00%
Weighted average target asset allocation - debt securities						75.00%	0.00%
Total allocation of the assets	100.00%	100.00%