Retirement Plans and Other Postretirement Benefits - Narrative (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Other Post Retirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected employer contributions for next fiscal year		$ 89
Defined benefit plan, contributions by employer	$ 52
Defined benefit plan, benefits paid	52
Nonqualified Plan [Member] | Retirement Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected employer contributions for next fiscal year		$ 157
Defined benefit plan, contributions by employer	80
Defined benefit plan, benefits paid	$ 1,300