Employee Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Defined Benefit Plan, Pension Plan with Projected Benefit Obligation in Excess of Plan Assets, Plan Assets					$ 8,493
Components of net periodic benefit costs:
Defined benefit plan assumptions, expected return on plan assets					7.50%
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent				35.00%
Pension Plans, Defined Benefit
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer			$ 3,200
Defined Benefit Plan, Benefit Obligation					$ 12,991
Components of net periodic benefit costs:
Interest cost	$ 104	$ 112	314	$ 338
Expected return on plan assets	(147)	(138)	(440)	(415)
Amortization of net loss	29	26	84	77
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Settlement	176
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Settlement		0	0	0
Net periodic benefit/cost	162	0	(42)	0
Defined Benefit Plan, Funded (Unfunded) Status of Plan					(4,498)
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax					$ 5,458
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate					3.40%
Other Postretirement Benefit Plans, Defined Benefit
Components of net periodic benefit costs:
Interest cost	0	1	2	3
Amortization of net loss	(1)	(1)	(4)	(5)
Net periodic benefit/cost	(1)	$ 0	$ (2)	$ (2)
Other Postretirement Benefit Plans, Defined Benefit | Employees Hired before January 1, 2003
Components of net periodic benefit costs:
Benefit based on highest average salary for number of consecutive years			5 years
Number of years for consecutive years calculation			10 years
Other Postretirement Benefit Plans, Defined Benefit | Employees Hired on or after January 1, 2003
Components of net periodic benefit costs:
Percent of annual salary to calculate benefit			2.00%
Before Settlement [Member] | Pension Plans, Defined Benefit
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Defined Benefit Plan, Benefit Obligation	12,006		$ 12,006
Defined Benefit Plan, Pension Plan with Projected Benefit Obligation in Excess of Plan Assets, Plan Assets	12,006		12,006
Components of net periodic benefit costs:
Defined Benefit Plan, Funded (Unfunded) Status of Plan	0		0
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax	$ 4,196		$ 4,196
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	4.00%		4.00%
Defined benefit plan assumptions, expected return on plan assets	7.50%		7.50%
Impact of Settlement [Member] | Pension Plans, Defined Benefit
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Defined Benefit Plan, Pension Plan with Projected Benefit Obligation in Excess of Plan Assets, Plan Assets	$ (510)		$ (510)
Components of net periodic benefit costs:
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Settlement	(510)
Defined Benefit Plan, Funded (Unfunded) Status of Plan	0		0
After Settlement [Member] | Pension Plans, Defined Benefit
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Defined Benefit Plan, Benefit Obligation	11,496		11,496
Defined Benefit Plan, Pension Plan with Projected Benefit Obligation in Excess of Plan Assets, Plan Assets	11,496		11,496
Components of net periodic benefit costs:
Defined Benefit Plan, Funded (Unfunded) Status of Plan	0		0
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax	$ 4,020		$ 4,020
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	4.00%		4.00%
Defined benefit plan assumptions, expected return on plan assets	7.50%		7.50%