CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Operating revenue:
Electric	$ 563,822	$ 468,366	$ 1,322,414	$ 1,137,456
Natural Gas	195,124	177,609	588,030	548,640
Other	10,444	5,704	19,032	11,713
Total operating revenue	769,390	651,679	1,929,476	1,697,809
Energy costs:
Purchased electricity	162,515	125,487	367,925	291,229
Electric generation fuel	56,448	32,974	116,866	96,598
Residential exchange	(17,592)	(16,167)	(43,394)	(40,801)
Purchased natural gas	62,829	61,257	217,844	216,133
Unrealized (gain) loss on derivative instruments, net	(61,276)	(12,162)	(84,278)	36,379
Utility operations and maintenance	150,167	148,120	310,707	303,042
Non-utility expense and other	9,566	15,841	19,472	28,803
Depreciation & Amortization	165,930	136,865	374,361	301,681
Conservation amortization	21,901	20,321	55,961	47,714
Taxes other than income taxes	76,837	68,793	187,147	174,297
Total operating expenses	627,325	581,329	1,522,611	1,455,075
Operating income (loss)	142,065	70,350	406,865	242,734
Other income (expense):
Other income	14,490	16,576	28,120	30,635
Other expense	(2,350)	(8,468)	(3,860)	(10,750)
Interest charges:
AFUDC	3,775	3,914	7,361	7,557
Interest expense	(90,407)	(106,793)	(179,767)	(195,677)
Income (loss) before income taxes	67,573	(24,421)	258,719	74,499
Income tax (benefit) expense	12,331	(1,188)	14,484	2,796
Net income (loss)	55,242	(23,233)	244,235	71,703
Subsidiaries [Member]
Operating revenue:
Electric	563,822	468,366	1,322,414	1,137,456
Natural Gas	195,124	177,609	588,030	548,640
Other	10,444	5,704	19,032	11,713
Total operating revenue	769,390	651,679	1,929,476	1,697,809
Energy costs:
Purchased electricity	162,515	125,487	367,925	291,229
Electric generation fuel	56,448	32,974	116,866	96,598
Residential exchange	(17,592)	(16,167)	(43,394)	(40,801)
Purchased natural gas	62,829	61,257	217,844	216,133
Unrealized (gain) loss on derivative instruments, net	(61,276)	(12,162)	(84,278)	36,379
Utility operations and maintenance	150,167	148,120	310,707	303,042
Non-utility expense and other	8,952	15,048	18,370	27,783
Depreciation & Amortization	165,803	136,816	374,165	301,587
Conservation amortization	21,901	20,321	55,961	47,714
Taxes other than income taxes	76,837	68,793	187,147	174,297
Total operating expenses	626,584	580,487	1,521,313	1,453,961
Operating income (loss)	142,806	71,192	408,163	243,848
Other income (expense):
Other income	11,427	12,862	22,461	24,145
Other expense	(2,350)	(8,468)	(3,860)	(10,750)
Interest charges:
AFUDC	3,775	3,914	7,361	7,557
Interest expense	(62,869)	(62,464)	(125,240)	(123,178)
Income (loss) before income taxes	92,789	17,036	308,885	141,622
Income tax (benefit) expense	14,425	1,999	31,051	15,264
Net income (loss)	$ 78,364	$ 15,037	$ 277,834	$ 126,358