Retirement Plans - Schedule of Target Allocation and Expected Long-Term Rate of Return by Asset Category (Detail)	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Percentage of Plan Assets at Year-end	100.00%	100.00%
Equity Securities in Financial Institutions [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Allocation, minimum	20.00%
Target Allocation, maximum	50.00%
Percentage of Plan Assets at Year-end	48.20%	46.70%
Total Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Allocation, minimum	30.00%
Target Allocation, maximum	60.00%
Percentage of Plan Assets at Year-end	47.00%	48.30%
Money Market Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Allocation, minimum	20.00%
Target Allocation, maximum	30.00%
Percentage of Plan Assets at Year-end	4.80%	5.00%

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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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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

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=58740216&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=58740216&loc=d3e2446-114920

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