Employee Benefit Plans Weighted Average Discount Rate Used to Determine the Net Periodic Postretirement Benefit Costs (Details) - Other Postretirement Benefit Plan	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Net periodic postretirement benefit costs	3.50%	3.25%	4.00%
Accumulated postretirement benefit obligations	3.61%	3.50%	3.25%