Benefit Plans, Weighted Average Asset Allocation Percentages (Details)	Dec. 31, 2020	Dec. 31, 2019
Weighted average asset allocations [Abstract]
Weighted average asset allocation percentages, Total	100.00%	100.00%
Equity Securities [Member]
Weighted average asset allocations [Abstract]
Weighted average asset allocation percentages, Total	55.80%	55.10%
Fixed Income Securities [Member]
Weighted average asset allocations [Abstract]
Weighted average asset allocation percentages, Total	27.80%	29.10%
Real Estate [Member]
Weighted average asset allocations [Abstract]
Weighted average asset allocation percentages, Total	0.30%	0.30%
Other [Member]
Weighted average asset allocations [Abstract]
Weighted average asset allocation percentages, Total	16.10%	15.50%