Defined Benefit Pension Plans (Components of Net Periodic Benefit Cost) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Qualified Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 537	$ 615
Interest cost	644	732
Expected return on plan assets	(1,158)	(1,129)
Amortization of prior service (credit) cost	(6)	(6)
Recognized net actuarial loss	207	312
Net periodic benefit cost	224	524
Non-Qualified Retirement Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	30	20
Interest cost	108	122
Expected return on plan assets	0	0
Amortization of prior service (credit) cost	0	0
Recognized net actuarial loss	62	61
Net periodic benefit cost	$ 200	$ 203