Estimated Future Benefit Payments (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014
Pension Plans
Schedule of Pension Expected Future Benefit Payments [Line Items]
2015	$ 4,712
2016	4,955
2017	5,186
2018	5,325
2019	5,864
2020 - 2024	34,931
Other Postretirement Benefit Plans, Defined Benefit
Schedule of Pension Expected Future Benefit Payments [Line Items]
2015	1,977
2016	2,093
2017	2,237
2018	2,368
2019	2,524
2020 - 2024	15,415
Supplemental Employee Retirement Plans, Defined Benefit
Schedule of Pension Expected Future Benefit Payments [Line Items]
2015	408
2016	403
2017	398
2018	392
2019	386
2020 - 2024	$ 2,252

Amount of benefits from a defined benefit plan expected to be paid in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (f)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

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- Definition

Amount of benefits from a defined benefit plan expected to be paid in the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of benefits from a defined benefit plan expected to be paid in the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of benefits from a defined benefit plan expected to be paid in the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of benefits from a defined benefit plan expected to be paid in the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Defined Benefit Plan, Expected Future Benefit Payments Thereafter

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