Pension and Postretirement Benefit Plans - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2005	Dec. 31, 2018 USD ($)	Dec. 31, 2015 plan
SERP I and SERP II
Defined Benefit Plan Disclosure [Line Items]
Number of defined benefit pension plans | plan			2
Defined benefit plan, participants amounts frozen, percentage		20.00%
Defined benefit plan, expected future employer contributions, next fiscal year | $		$ 286
PRBP
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, maximum annual payment, percentage	120.00%