Defined Benefit Pension Plans (Components of Net Periodic Benefit Cost) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Qualified Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 537	$ 537
Interest cost	669	644
Expected return on plan assets	(1,236)	(1,158)
Amortization of prior service (credit) cost	(6)	(6)
Recognized net actuarial loss	279	207
Net periodic benefit cost	243	224
Non-Qualified Retirement Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	32	30
Interest cost	107	108
Expected return on plan assets	0	0
Amortization of prior service (credit) cost	0	0
Recognized net actuarial loss	65	62
Net periodic benefit cost	$ 204	$ 200