XML 90 R73.htm IDEA: XBRL DOCUMENT v3.8.0.1
Postretirement Benefits Other Than Pensions - Expected Future Benefit Payments (Detail) - Other Postretirement Benefit Plan [Member]
$ in Thousands
Dec. 31, 2017
USD ($)
Defined Benefit Plan Disclosure [Line Items]  
2018 $ 343
2019 327
2020 306
2021 284
2022 266
2023-2027 $ 1,078