Schedule of Expected Benefit Payments (Detail) $ in Thousands	Dec. 31, 2017 USD ($)
Pension Plans, Defined Benefit
Schedule of Pension Expected Future Benefit Payments [Line Items]
2018	$ 15,350
2019	5,812
2020	5,877
2021	5,966
2022	5,978
2023 – 2027	30,440
Total 10-year estimated future benefit payments	69,423
Other Pension Plans, Defined Benefit
Schedule of Pension Expected Future Benefit Payments [Line Items]
2018	282
2019	301
2020	311
2021	302
2022	287
2023 – 2027	1,212
Total 10-year estimated future benefit payments	$ 2,695

Defined benefit plan, expected future benefit payments.

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- Definition

Schedule of Pension Expected Future Benefit Payments [Line Items]

+ References

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

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

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

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

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