Employee Benefit Plans (Assumed Health Care Cost Trend Rates) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Assumed annual increases in Medicare Part B trends after eight years	4.50%	4.50%
Defined Benefit Plan, Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rates [Abstract]
Effect on total of service and interest cost components, 1% Increase	$ 4
Effect on total of service and interest cost components, 1% Decrease	(4)
Effect on benefit obligation, 1% Increase	71
Effect on benefit obligation, 1% Decrease	$ (67)
Minimum
Defined Benefit Plan Disclosure [Line Items]
Assumed annual increases in Medicare Part B trends for next eight years	0.30%	1.29%
Maximum
Defined Benefit Plan Disclosure [Line Items]
Assumed annual increases in Medicare Part B trends for next eight years	18.23%	17.92%