Employee Benefit Plans (Summary of Estimated Future Benefit Payments) (Details) $ in Thousands	Dec. 31, 2018 USD ($)
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
2019	$ 16,400
2020	17,363
2021	18,173
2022	18,532
2023	16,904
Next 5 years	73,508
Total	160,880
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
2019	11,993
2020	12,125
2021	12,058
2022	12,253
2023	12,072
Next 5 years	57,896
Total	$ 118,397