Retirement Agreements and Other Postretirement Benefit Plan Amounts in Accumulated Other Comprehensive Income, Pre-tax, to be Recognized as Components of Net Periodic Benefit Costs (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Retirement Benefits [Abstract]
Amortization of unrecognized prior service cost	$ 0
Amortization of unrecognized loss	0
Net periodic benefit cost at end of year	$ 0