Employee Benefit Plans - Future Benefit Payments Under Pension Plans (Detail) $ in Thousands	Dec. 31, 2017 USD ($)
Pension Plan
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2018	$ 1,178
2019	1,212
2020	1,288
2021	1,365
2022	1,453
2023 - 2027	8,246
Retirement Plan \| La Barge
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2018	561
2019	546
2020	528
2021	506
2022	482
2023 - 2027	$ 2,022

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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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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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