Pension and Other Postretirement Benefits (Details 10) $ in Thousands	Dec. 31, 2018 USD ($)
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Estimated future employer contributions in next fiscal year	$ 4,706
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
2019	29,550
2020	29,414
2021	29,573
2022	29,224
2023	29,042
Years 2024-2028	144,754
Total	291,557
Other postretirement benefit plans [Member]
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
2019	3,515
2020	3,332
2021	3,065
2022	2,892
2023	2,688
Years 2024-2028	11,093
Total	$ 26,585