Employee Benefit Plans (Details 1) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Employee benefits plans
Fair value of plan assets
Pension Plan
Employee benefits plans
Fair value of plan assets	$ 118,092	$ 107,862	$ 126,013
Funded pension plan assets, by asset category (as a percent)	100.00%	100.00%
Pension Plan | Total investments, excluding investments valued at NAV
Employee benefits plans
Fair value of plan assets	$ 112,185	$ 93,518
Pension Plan | Quoted Prices in Active Markets for Identical Assets (Level 1)
Employee benefits plans
Fair value of plan assets	107,943	93,518
Pension Plan | Significant Other Observable Inputs (Level 2)
Employee benefits plans
Fair value of plan assets	4,242	0
Pension Plan | Significant Unobservable Inputs (Level 3)
Employee benefits plans
Fair value of plan assets	0	0
Pension Plan | Equity securities
Employee benefits plans
Fair value of plan assets	$ 68,563	$ 71,384
Funded pension plan assets, by asset category (as a percent)	58.00%	66.00%
Pension Plan | Equity securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Employee benefits plans
Fair value of plan assets	$ 68,563	$ 71,384
Pension Plan | Equity securities | Significant Other Observable Inputs (Level 2)
Employee benefits plans
Fair value of plan assets	0	0
Pension Plan | Equity securities | Significant Unobservable Inputs (Level 3)
Employee benefits plans
Fair value of plan assets	0	0
Pension Plan | Debt securities
Employee benefits plans
Fair value of plan assets	$ 43,622	$ 22,134
Funded pension plan assets, by asset category (as a percent)	37.00%	21.00%
Pension Plan | Debt securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Employee benefits plans
Fair value of plan assets	$ 39,380	$ 22,134
Pension Plan | Debt securities | Significant Other Observable Inputs (Level 2)
Employee benefits plans
Fair value of plan assets	4,242	0
Pension Plan | Debt securities | Significant Unobservable Inputs (Level 3)
Employee benefits plans
Fair value of plan assets	0	0
Pension Plan | Other
Employee benefits plans
Fair value of plan assets	$ 5,907	$ 14,344
Funded pension plan assets, by asset category (as a percent)	5.00%	13.00%
Pension Plan | Other | Investments valued at NAV
Employee benefits plans
Fair value of plan assets	$ 5,907	$ 14,344