Employee Benefit Plans - Asset Allocations for Funded Pension Plans (Detail)							12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 Equity securities [Member]	Dec. 31, 2011 Equity securities [Member]	Dec. 31, 2012 Debt securities [Member]	Dec. 31, 2011 Debt securities [Member]	Dec. 31, 2012 Target Asset Allocation 2013 [Member]	Dec. 31, 2012 Target Asset Allocation 2013 [Member] Equity securities [Member]	Dec. 31, 2012 Target Asset Allocation 2013 [Member] Debt securities [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Asset allocation, Total	100.00%	100.00%	68.00%	69.00%	32.00%	31.00%
Target Allocation Percentage of Assets, Total							100.00%	71.00%	29.00%

Percentage of fair value of investments (categorized by debt securities, equity securities, real estate and other plan assets) to the fair value of plan assets held.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 5

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e2446-114920

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (d)(1)

-URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 5

-Subparagraph d(1)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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

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