Defined Benefit Pension Plans (Components of Net Periodic Benefit Cost) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Qualified Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 537	$ 614	$ 1,074	$ 1,229
Interest cost	644	732	1,288	1,464
Expected return on plan assets	(1,159)	(1,128)	(2,317)	(2,257)
Amortization of prior service (credit) cost	(5)	(5)	(11)	(11)
Recognized net actuarial loss	207	312	414	624
Net periodic benefit cost	224	525	448	1,049
Non-Qualified Retirement Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	31	19	61	39
Interest cost	108	123	216	245
Expected return on plan assets	0	0	0	0
Amortization of prior service (credit) cost	0	0	0	0
Recognized net actuarial loss	61	61	123	122
Net periodic benefit cost	$ 200	$ 203	$ 400	$ 406