Retirement Plans Retirement Plans, Fair Value Reconciliation of Level 3 Retirement Account Plan Investments (Details) - RAP - Group annuity contracts - Fair Value, Inputs, Level 3 - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Fair value of group annuity contract at beginning of period	$ 50,055	$ 47,265
Return on plan assets	3,499	5,495
Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Decrease for Settlement	(2,688)	(2,704)
Fair value of group annuity contract at end of period	$ 50,866	$ 50,055