Benefit Plans Level 3 Rollforward (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Actual return on plan assets:
Defined Benefit Plan, Plan Assets, Foreign Currency Translation Gain (Loss)	$ 15,548	$ (11,532)
Defined Benefit Plan, Plan Assets, Amount	964,774	862,951	$ 919,782
Real Asset Mutual Funds, Commodities
Actual return on plan assets:
Defined Benefit Plan, Plan Assets, Amount	47,697	40,267
Real Asset Mutual Funds, Commodities | Fair Value, Inputs, Level 3 [Member]
Actual return on plan assets:
Defined Benefit Plan, Plan Assets, Amount	0	0
Fixed Income Mutual Funds, Insurance Contracts
Actual return on plan assets:
Defined Benefit Plan, Plan Assets, Amount	38,945	24,313
Fixed Income Mutual Funds, Insurance Contracts | Fair Value, Inputs, Level 3 [Member]
Actual return on plan assets:
Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increase (Decrease) for Actual Return (Loss) on Plan Assets Still Held	14	14
Defined Benefit Plan Sales, Total	(54)	(85)
Defined Benefit Plan, Purchases, Total	83	82
Defined Benefit Plan, Plan Assets, Foreign Currency Translation Gain (Loss)	(18)	(64)
Defined Benefit Plan, Plan Assets, Amount	$ 1,486	$ 1,461	$ 1,514