Employee and Retiree Benefit Plans (Benefit Payments, Reflected Expected Future Service as Appropriate which are Expected to be Paid in Future Years from Assets of Plans or by Company) (Details) $ in Thousands	Dec. 31, 2016 USD ($)
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
2017	$ 38,532
2018	38,896
2019	39,833
2020	40,848
2021	41,653
2022-2026	221,350
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
2017	6,161
2018	6,319
2019	6,435
2020	6,621
2021	6,824
2022-2026	$ 36,326

Employee and Retiree Benefit Plans (Benefit Payments, Reflected Expected Future Service as Appropriate which are Expected to be Paid in Future Years from Assets of Plans or by Company) (Details)
$ in Thousands

Dec. 31, 2016

USD ($)

Defined Benefit Plan Disclosure [Line Items]

$ 38,532

38,896

39,833

40,848

41,653

221,350