Leases (Balance Sheet) (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Leases [Abstract]
Operating lease right-of-use asset	$ 184,957	$ 172,167
Operating lease liabilities	20,398	19,204
Operating lease liabilities	172,510	160,980
Operating Lease, Liability	192,908	180,184
Finance Lease, Right-of-Use Asset	105,020	881
Finance Lease, Liability, Current	1,742	475
Finance Lease, Liability, Noncurrent	105,303	320
Finance Lease, Liability	$ 107,045	$ 795
Operating Lease, Weighted Average Remaining Lease Term	22 years 9 months 18 days	18 years 11 months 19 days
Finance Lease, Weighted Average Remaining Lease Term	20 years 1 month 24 days	2 years
Operating Lease, Weighted Average Discount Rate, Percent	3.27%	3.59%
Finance Lease, Weighted Average Discount Rate, Percent	3.07%	2.98%
Operating Leased Assets [Line Items]
Finance Lease, Right-of-Use Asset	$ 105,020	$ 881
Common Plant
Leases [Abstract]
Finance Lease, Right-of-Use Asset	61,227	881
Operating Leased Assets [Line Items]
Finance Lease, Right-of-Use Asset	61,227	881
Electric Transmission
Leases [Abstract]
Finance Lease, Right-of-Use Asset	43,793	0
Operating Leased Assets [Line Items]
Finance Lease, Right-of-Use Asset	$ 43,793	$ 0