Retirement and Compensation Plans Net periodic pension costs incurred by the plans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Service Cost	$ 4,549	$ 5,973	$ 5,552
Defined Benefit Plan, Interest Cost	13,273	13,642	14,124
Defined Benefit Plan, Expected Return (Loss) on Plan Assets	(18,827)	(22,247)	(19,184)
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	0	46	131
Defined Benefit Plan, Amortization of Gain (Loss)	8,913	12,507	10,121
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	0	(17,406)	0
Defined Benefit Plan, Benefit Obligation, Special and Contractual Termination Benefits	0	5,168
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	7,908	32,495	10,744
Net periodic pension cost individual entity share	2,533	9,956	3,404
Defined Benefit Plan, Expected Amortization of Gain (Loss), Next Fiscal Year	11,200
Defined Benefit Plan, Estimated Future Employer Contributions in Next Fiscal Year	15,000
Multiemployer Plans, Minimum Contribution	4,800
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months	16,500
Defined Benefit Plan, Expected Future Benefit Payment, Year Two	18,700
Defined Benefit Plan, Expected Future Benefit Payment, Year Three	19,100
Defined Benefit Plan, Expected Future Benefit Payment, Year Four	20,900
Defined Benefit Plan, Expected Future Benefit Payment, Year Five	20,700
Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter	121,200
Other Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Service Cost	467	539	436
Defined Benefit Plan, Interest Cost	992	958	1,003
Defined Benefit Plan, Expected Return (Loss) on Plan Assets	0	0	0
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	0	0	0
Defined Benefit Plan, Amortization of Gain (Loss)	1,066	1,353	1,172
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	0	0	0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	2,525	2,850	2,611
Net periodic pension cost individual entity share	1,449	$ 1,671	$ 1,551
Defined Benefit Plan, Expected Amortization of Gain (Loss), Next Fiscal Year	1,300
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months	3,600
Defined Benefit Plan, Expected Future Benefit Payment, Year Two	4,300
Defined Benefit Plan, Expected Future Benefit Payment, Year Three	3,400
Defined Benefit Plan, Expected Future Benefit Payment, Year Four	4,100
Defined Benefit Plan, Expected Future Benefit Payment, Year Five	3,000
Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter	$ 10,000