Employee Benefit Plans (Schedule of Allocation of Plan Assets) (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Pension Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Allocation of plan assets	100.00%	100.00%
Pension Benefit Plan [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Allocation of plan assets	59.70%	59.10%
Target plan allocations	55.00%
Pension Benefit Plan [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Allocation of plan assets	36.60%	37.80%
Target plan allocations	38.00%
Pension Benefit Plan [Member] | Cash [Member]
Defined Benefit Plan Disclosure [Line Items]
Allocation of plan assets	1.00%	1.30%
Target plan allocations	2.00%
Pension Benefit Plan [Member] | Commodities [Member]
Defined Benefit Plan Disclosure [Line Items]
Allocation of plan assets	2.70%	1.80%
Target plan allocations	5.00%
Other Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Allocation of plan assets	100.00%	100.00%
Other Benefits Plan [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Allocation of plan assets	54.10%	50.00%
Target plan allocations	43.00%
Other Benefits Plan [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Allocation of plan assets	43.30%	47.40%
Target plan allocations	50.00%
Other Benefits Plan [Member] | Cash [Member]
Defined Benefit Plan Disclosure [Line Items]
Allocation of plan assets	2.60%	2.40%
Target plan allocations	2.00%
Other Benefits Plan [Member] | Commodities [Member]
Defined Benefit Plan Disclosure [Line Items]
Allocation of plan assets	0.00%	0.20%
Target plan allocations	5.00%