XML 110 R98.htm IDEA: XBRL DOCUMENT v3.10.0.1
Schedule of Net Periodic Benefit Cost for Postretirement Health Care and Life Insurance Plan (Detail) - Other Benefits - USD ($)
$ in Thousands
 3 Months Ended 4 Months Ended 5 Months Ended 6 Months Ended 12 Months Ended
Jun. 30, 2018
Jun. 30, 2017
Jul. 31, 2017
Dec. 31, 2017
Jun. 30, 2018
Jun. 30, 2017
Mar. 31, 2017
Net Period Benefit Cost Assumptions [Line Items]              
Service cost $ 15     $ 29 $ 30    
Interest cost 29     75 58    
Amortization of prior service cost (75)       (150)    
Amortization of net (loss) gain 11       22    
Net periodic pension cost $ (20)     $ 104 $ (40)    
Predecessor              
Net Period Benefit Cost Assumptions [Line Items]              
Service cost   $ 17 $ 23     $ 38 $ 81
Interest cost   48 64     99 201
Amortization of prior service cost   (695) (927)     (1,783) (4,346)
Amortization of net (loss) gain   (252) (335)     (535) (1,138)
Net periodic pension cost   $ (882) $ (1,175)     $ (2,181) $ (5,202)