Benefit Plans (Weighted Average Asset Allocations) (Details)	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Weighted average asset allocations	100.00%	100.00%
Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted average asset allocations	3.50%	2.60%
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted average asset allocations	53.00%	55.10%
Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted average asset allocations	43.50%	42.30%