Benefit Plans, Weighted Average Asset Allocation by Asset Category (Details)	Dec. 31, 2019	Dec. 31, 2018
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	55.10%	54.90%
Fixed Income Securities [Member]
Weighted average asset allocations [Abstract]
Weighted average asset allocation percentages, Total	29.10%	38.30%
Real Estate [Member]
Weighted average asset allocations [Abstract]
Weighted average asset allocation percentages, Total	0.30%	0.80%
Other [Member]
Weighted average asset allocations [Abstract]
Weighted average asset allocation percentages, Total	15.50%	6.00%