Pension Benefit Plans - Components of Pension Expense and Other Postretirement Benefit Expense(Details) - HNH - Pension Plans, Defined Benefit - USD ($)
$ in Thousands
3 Months Ended 9 Months Ended
Sep. 30, 2016
Sep. 30, 2015
Sep. 30, 2016
Sep. 30, 2015
Defined Benefit Plans Disclosure [Line Items]        
Service cost $ 0 $ 9 $ 0 $ 9
Interest cost 5,720 6,404 17,705 16,828
Expected return on plan assets (7,342) (7,520) (22,184) (19,550)
Administrative costs 314 315 894 504
Amortization of actuarial loss 1,990 1,482 6,240 4,672
Total $ 682 $ 690 $ 2,655 $ 2,463