Other Income and Other Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Other income:
Interest income	$ 2,755	$ 2,699	$ 6,032	$ 5,001
Investment gains (losses) - net	2,826	0	2,826	0
Miscellaneous	137	5	145	28
Total other income	16,670	12,885	29,239	20,054
Other expense:
Non-operating costs	(2,290)	(3,481)	(4,948)	(6,185)
Investment losses (gains) — net	0	(491)	60	(729)
Miscellaneous	(1,746)	(378)	(3,932)	(1,794)
Total other expense	(4,036)	(4,350)	(8,820)	(8,708)
APS
Other income:
Interest income	2,183	1,504	4,524	3,054
Miscellaneous	137	6	145	28
Total other income	13,272	11,691	24,905	18,107
Other expense:
Non-operating costs	(2,113)	(3,049)	(4,595)	(5,517)
Miscellaneous	(1,746)	(379)	(3,932)	(1,789)
Total other expense	(3,859)	(3,428)	(8,527)	(7,306)
SCR deferral
Other income:
Debt return on Four Corners SCR deferrals (Note 4)	4,249	4,887	7,389	9,731
SCR deferral | APS
Other income:
Debt return on Four Corners SCR deferrals (Note 4)	4,249	4,887	7,389	9,731
Ocotillo deferral
Other income:
Debt return on Four Corners SCR deferrals (Note 4)	6,703	5,294	12,847	5,294
Ocotillo deferral | APS
Other income:
Debt return on Four Corners SCR deferrals (Note 4)	$ 6,703	$ 5,294	$ 12,847	$ 5,294