Benefit Plans and Other Postretirement Benefits, Projected Benefit Payments (Details) $ in Thousands	Dec. 31, 2016 USD ($)
Pension Plans
Defined Benefit Plan, Gross Projected Benefit Payments [Abstract]
2017	$ 79,506
2018	78,738
2019	80,914
2020	81,095
2021	82,084
2022-2026	417,876
Postretirement Benefit Plan
Defined Benefit Plan, Gross Projected Benefit Payments [Abstract]
2017	33,912
2018	33,652
2019	33,467
2020	33,991
2021	33,588
2022-2026	156,773
Expected Medicare Part D Subsidies [Abstract]
2017	2,140
2018	2,266
2019	2,383
2020	2,475
2021	2,574
2022-2026	14,246
Defined Benefit Plan, Net Projected Benefit Payments [Abstract]
2017	31,772
2018	31,386
2019	31,084
2020	31,516
2021	31,014
2022-2026	$ 142,527