Note Employee benefits (Projected benefit payments) (Detail) $ in Thousands	Dec. 31, 2018 USD ($)
Pension Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
2019	$ 46,976
2020	44,435
2021	44,616
2022	44,883
2023	45,175
2024- 2028	226,988
OPEB Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
2019	8,128
2020	6,645
2021	6,834
2022	7,026
2023	7,244
2024- 2028	$ 39,774

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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e1928-114920

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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 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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