Employee Benefit Plans (Defined Benefit Plans Disclosure) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2,580	$ 2,306
Interest cost	1,198	1,259
Expected return on plan assets	(1,285)	(1,224)
Amortization of prior service cost	74	78
Amortization of prior actuarial loss	1,081	857
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements	257	0
Total	3,905	3,276
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	721	1,016
Interest cost	565	643
Expected return on plan assets	0	0
Amortization of prior service cost	(156)	0
Amortization of prior actuarial loss	457	616
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements	0	0
Total	$ 1,587	$ 2,275