Schedule of Target Assets Allocation (Detail)	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Other securities, Target Allocation	100.00%
Total	100.00%	100.00%
Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Other securities, Target Allocation	54.00%
Total	55.00%	59.00%
Debt Securities
Defined Benefit Plan Disclosure [Line Items]
Other securities, Target Allocation	30.00%
Total	31.00%	29.00%
Hedge Funds
Defined Benefit Plan Disclosure [Line Items]
Other securities, Target Allocation	8.00%
Total	7.00%	4.00%
Real Estate
Defined Benefit Plan Disclosure [Line Items]
Other securities, Target Allocation	8.00%
Total	7.00%	7.00%
Cash and Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Other securities, Target Allocation	0.00%
Total	0.00%	1.00%

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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 5
-Subparagraph (c)(i)
-URI http://asc.fasb.org/extlink&oid=58740216&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)(i)
-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920

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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.

+ References

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=58740216&loc=d3e2446-114920

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(1)
-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920

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