Pension Plans - Weighted-Average Target Allocations of Plan Assets (Detail)	12 Months Ended
Dec. 31, 2014
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocation range, Minimum	30.00%
Target plan asset allocation range, Maximum	80.00%
Target plan asset allocations	60.00%
Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocation range, Minimum	20.00%
Target plan asset allocation range, Maximum	70.00%
Target plan asset allocations	40.00%
Cash and Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocation range, Minimum	0.00%
Target plan asset allocation range, Maximum	10.00%

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Target allocation of investments of this type to total plan assets presented on a weighted average basis.

+ References

Reference 1: 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=35743120&loc=d3e1928-114920

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=35743120&loc=d3e2446-114920

+ Details

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- Definition

Target allocation maximum percentage of investments of this type to total plan assets presented on a weighted average basis.

+ References

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Target allocation minimum percentage of investments of this type to total plan assets presented on a weighted average basis.

+ References

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