Pension and Other Post Retirement Benefit Plans - Narrative (Details) - USD ($)		12 Months Ended
	Mar. 01, 2005	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Percentage of employees covered by plan		13.00%
Minimum participant attained age	55 years
Requisite service period (at least)	10 years
Release of benefit obligation for plan settlement			$ 4,600,000
Settlement charge			(3,803,000)
Settlement loss recognized			761,000
Accumulated benefit obligation		73,193,000	82,157,000
Minimum required contribution in next fiscal year		$ 0
Requisite service period		1000 hours
Employer percentage contribution		2.00%
Vesting period		5 years
Expense recognized in the period		$ 5,114,000	3,691,000	$ 3,441,000
Percentage of the premiums paid by plan participants		100.00%
Curtailment gain				2,157,000
Post retirement plan expense			(301,000)	(2,437,000)
Fair value of plan assets		$ 76,736,000	85,213,000	83,557,000
Net periodic pension benefit cost		(1,693,000)	654,000	509,000
Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		71,277,000	78,280,000
Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		$ 5,459,000	$ 6,933,000
Contribution for first 3%
Defined Benefit Plan Disclosure [Line Items]
Amount of discretionary contributions made by employer to defined contribution plan, percent		100.00%
Maximum annual contribution percentage per employee		3.00%
Contribution after first 3%
Defined Benefit Plan Disclosure [Line Items]
Amount of discretionary contributions made by employer to defined contribution plan, percent		50.00%
Maximum annual contribution percentage per employee		3.00%
Minimum
Defined Benefit Plan Disclosure [Line Items]
Age of plan participants		55 years
Minimum | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Maturities of debt securities		15 days	15 days
Maximum
Defined Benefit Plan Disclosure [Line Items]
Age of plan participants		65 years
Maximum | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Maturities of debt securities		8 years 2 months 25 days	8 years 10 months
Weighted Average | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Maturities of debt securities		4 years 3 months 15 days	4 years 6 months 12 days
Non-qualified plans
Defined Benefit Plan Disclosure [Line Items]
Net periodic pension benefit cost		$ 161,000	$ 213,000	$ 217,000