Regulatory Matters - Schedule of Regulatory Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Detail of regulatory liabilities
Total regulatory liabilities	$ 2,333,351	$ 2,795,484
Less: current regulatory liabilities	271,575	296,271
Total noncurrent regulatory liabilities	2,061,776	2,499,213
Asset retirement obligations
Detail of regulatory liabilities
Total regulatory liabilities	354,002	614,683
Other postretirement benefits
Detail of regulatory liabilities
Total regulatory liabilities	270,604	374,816
Removal costs
Detail of regulatory liabilities
Total regulatory liabilities	106,889	119,580
Deferred Fuel and Purchased Power MTM Costs [Member]
Detail of regulatory liabilities
Total regulatory liabilities	96,367	107,601
Income taxes — change in rates
Detail of regulatory liabilities
Total regulatory liabilities	64,806	67,678
Four Corners coal reclamation
Detail of regulatory liabilities
Total regulatory liabilities	52,592	55,392
Income taxes — deferred investment tax credit
Detail of regulatory liabilities
Total regulatory liabilities	48,035	49,601
Spent nuclear fuel
Detail of regulatory liabilities
Total regulatory liabilities	39,217	45,282
Renewable energy program
Detail of regulatory liabilities
Total regulatory liabilities	35,720	38,640
FERC transmission true up
Detail of regulatory liabilities
Total regulatory liabilities	22,895	34,303
Property tax deferral
Detail of regulatory liabilities
Total regulatory liabilities	15,521	20,192
Sundance maintenance
Detail of regulatory liabilities
Total regulatory liabilities	16,893	13,797
Demand side management
Detail of regulatory liabilities
Total regulatory liabilities	8,461	5,417
Tax expense adjustor mechanism
Detail of regulatory liabilities
Total regulatory liabilities	4,835	4,835
Other
Detail of regulatory liabilities
Total regulatory liabilities	3,092	2,103
ACC | Excess deferred income taxes - ACC - Tax Cuts and Jobs Act
Detail of regulatory liabilities
Total regulatory liabilities	971,545	1,012,448
FERC | Excess deferred income taxes - ACC - Tax Cuts and Jobs Act
Detail of regulatory liabilities
Total regulatory liabilities	$ 221,877	$ 229,116