Pension Plans and Other Postretirement Benefits - Defined Benefit Plan Estimated Future Benefit Payments (Detail) $ in Thousands	Dec. 31, 2017 USD ($)
Pension Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
2018	$ 88,407
2019	94,317
2020	98,753
2021	103,968
2022	107,298
2023 through 2027	594,900
Other Postretirement Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
2018	7,318
2019	7,207
2020	7,055
2021	4,402
2022	4,302
2023 through 2027	$ 19,830

Pension plans, postretirement and other employee benefits.

No definition available.

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- Definition

Amount of benefits for defined benefit plan expected to be paid in five fiscal years after fifth fiscal year following latest fiscal year.

+ 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 (f)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

+ Details

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- Definition

Amount of benefits for defined benefit plan expected to be paid in next fiscal year following latest fiscal year.

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- Definition

Amount of benefits for defined benefit plan expected to be paid in fifth fiscal year following latest fiscal year.

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- Definition

Amount of benefits for defined benefit plan expected to be paid in fourth fiscal year following latest fiscal year.

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- Definition

Amount of benefits for defined benefit plan expected to be paid in third fiscal year following latest fiscal year.

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- Definition

Amount of benefits for defined benefit plan expected to be paid in second fiscal year following latest fiscal year.

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