Retirement Plans, Fair Value of Pension Plan Investments Table (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Pension Plan Investments
Money market account	$ 7,159	$ 9,577
Common /collective trust funds	138,020	133,210
Mutual funds	198,120	188,823
Group annuity contracts	47,265
Total Retirement Account Plan Investments	390,564	331,610
Fair Value, Inputs, Level 1
Pension Plan Investments
Money market account	7,159	9,577
Common /collective trust funds	138,020	133,210
Mutual funds	198,120	188,823
Group annuity contracts	0
Total Retirement Account Plan Investments	343,299	331,610
Fair Value, Inputs, Level 2
Pension Plan Investments
Money market account	0	0
Common /collective trust funds	0	0
Mutual funds	0	0
Group annuity contracts	0
Total Retirement Account Plan Investments	0	0
Fair Value, Inputs, Level 3
Pension Plan Investments
Money market account	0	0
Common /collective trust funds	0	0
Mutual funds	0	0
Group annuity contracts	47,265
Total Retirement Account Plan Investments	$ 47,265	$ 0