Regulatory Matters - Schedule of Regulatory Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Detail of regulatory liabilities
Total regulatory liabilities	$ 2,041,781	$ 2,175,788
Less: current regulatory liabilities	230,551	209,923
Total non-current regulatory liabilities	1,811,230	1,965,865
Asset retirement obligations
Detail of regulatory liabilities
Total regulatory liabilities	303,303	392,383
Other postretirement benefits
Detail of regulatory liabilities
Total regulatory liabilities	205,107	226,726
Removal costs
Detail of regulatory liabilities
Total regulatory liabilities	82,823	94,368
Income taxes — deferred investment tax credit
Detail of regulatory liabilities
Total regulatory liabilities	67,435	68,521
Income taxes — change in rates
Detail of regulatory liabilities
Total regulatory liabilities	59,578	60,667
Four Corners coal reclamation
Detail of regulatory liabilities
Total regulatory liabilities	57,493	55,917
Renewable energy standard
Detail of regulatory liabilities
Total regulatory liabilities	48,327	43,251
Spent nuclear fuel
Detail of regulatory liabilities
Total regulatory liabilities	29,415	33,154
Demand side management
Detail of regulatory liabilities
Total regulatory liabilities	26,333	14,374
Sundance maintenance
Detail of regulatory liabilities
Total regulatory liabilities	21,537	19,989
Property tax deferral
Detail of regulatory liabilities
Total regulatory liabilities	7,826	10,850
Tax expense adjustor mechanism
Detail of regulatory liabilities
Total regulatory liabilities	4,645	4,835
FERC Transmission true up
Detail of regulatory liabilities
Total regulatory liabilities	0	1,869
Other
Detail of regulatory liabilities
Total regulatory liabilities	1,642	3,873
ACC | Excess deferred income taxes - Tax Act
Detail of regulatory liabilities
Total regulatory liabilities	914,436	930,344
FERC | Excess deferred income taxes - Tax Act
Detail of regulatory liabilities
Total regulatory liabilities	$ 211,881	$ 214,667