Pension and Supplemental Executive Retirement Plans - Defined Benefit Plan Activity (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	May 31, 2014
Weighted average assumptions used to determine the benefit obligation
Discount rate used to re-measure pension obligation					4.46%
Components of net periodic pension cost
Service cost	$ 0	$ 0	$ 0	$ 0
Interest cost	88	90	264	270
Expected return on plan assets	(93)	(86)	(279)	(258)
Amortization of net actuarial loss	77	60	230	180
Amortization of prior service costs	0	0	0	0
Net periodic pension cost	72	64	215	192
Contributions Paid	$ 179	$ 145	$ 337	$ 261