REGULATORY ASSETS AND LIABILITIES (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2017	Dec. 31, 2019
SCHEDULE OF REGULATED ASSETS AND LIABILITIES [Line Items]
Kansas Gas Service tax reform regulatory liability	$ 81,500,000		$ 81,500,000
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent			21.00%		35.00%
Regulatory Assets, Current	71,748,000		$ 71,748,000			$ 47,440,000
Regulatory Assets, Noncurrent	364,117,000		364,117,000			391,036,000
Regulatory Liability, Current	(20,454,000)		(20,454,000)			(45,201,000)
Regulatory Liability, Noncurrent	(555,258,000)		(555,258,000)			(503,518,000)
Net regulatory assets (liabilities), current	51,294,000		51,294,000			2,239,000
Net regulatory assets (liabilities), noncurrent	(191,141,000)		(191,141,000)			(112,482,000)
Net Regulatory Assets	(139,847,000)		(139,847,000)			(110,243,000)
Reduction in income tax expense for the amortization of the regulatory liability associated with excess ADIT that was returned to customers	2,200,000	$ 1,400,000	11,600,000	$ 10,300,000
Income tax rate changes [Member] [Domain]
SCHEDULE OF REGULATED ASSETS AND LIABILITIES [Line Items]
Regulatory Liability, Current	0		0			(10,297,000)
Regulatory Liability, Noncurrent	(555,258,000)		(555,258,000)			(503,518,000)
Regulatory Liabilities	(555,258,000)		(555,258,000)			(513,815,000)
Over-recovered purchased-gas costs [Member]
SCHEDULE OF REGULATED ASSETS AND LIABILITIES [Line Items]
Regulatory Liability, Current	(20,454,000)		(20,454,000)			(27,623,000)
Regulatory Liability, Noncurrent	0		0			0
Regulatory Liabilities	(20,454,000)		(20,454,000)			(27,623,000)
Total regulated liabilities [Member]
SCHEDULE OF REGULATED ASSETS AND LIABILITIES [Line Items]
Regulatory Liability, Current	(20,454,000)		(20,454,000)			(45,201,000)
Regulatory Liability, Noncurrent	(555,258,000)		(555,258,000)			(503,518,000)
Regulatory Liabilities	(575,712,000)		(575,712,000)			(548,719,000)
Under-recovered purchased-gas costs [Member]
SCHEDULE OF REGULATED ASSETS AND LIABILITIES [Line Items]
Regulatory Assets, Current	22,485,000		22,485,000			17,172,000
Regulatory Assets, Noncurrent	0		0			0
Regulatory Assets	22,485,000		22,485,000			17,172,000
Pension and postretirement benefit costs [Member]
SCHEDULE OF REGULATED ASSETS AND LIABILITIES [Line Items]
Regulatory Assets, Current	21,132,000		21,132,000			21,213,000
Regulatory Assets, Noncurrent	345,006,000		345,006,000			373,266,000
Regulatory Assets	366,138,000		366,138,000			394,479,000
Weather normalization [Member]
SCHEDULE OF REGULATED ASSETS AND LIABILITIES [Line Items]
Regulatory Assets, Current	4,289,000		4,289,000
Regulatory Assets, Noncurrent	0		0
Regulatory Assets	4,289,000		4,289,000
Regulatory Liability, Current						(7,281,000)
Regulatory Liability, Noncurrent						0
Regulatory Liabilities						(7,281,000)
Reacquired debt costs [Member]
SCHEDULE OF REGULATED ASSETS AND LIABILITIES [Line Items]
Regulatory Assets, Current	812,000		812,000			812,000
Regulatory Assets, Noncurrent	5,068,000		5,068,000			5,677,000
Regulatory Assets	5,880,000		5,880,000			6,489,000
MGP Costs [Member] [Member]
SCHEDULE OF REGULATED ASSETS AND LIABILITIES [Line Items]
Regulatory Assets, Current	98,000		98,000			98,000
Regulatory Assets, Noncurrent	11,636,000		11,636,000			9,709,000
Regulatory Assets	11,734,000		11,734,000			9,807,000
Ad valorem tax [Member]
SCHEDULE OF REGULATED ASSETS AND LIABILITIES [Line Items]
Regulatory Assets, Current	5,260,000		5,260,000			2,921,000
Regulatory Assets, Noncurrent	0		0			0
Regulatory Assets	5,260,000		5,260,000			2,921,000
Other regulatory assets [Member]
SCHEDULE OF REGULATED ASSETS AND LIABILITIES [Line Items]
Regulatory Assets, Current	2,773,000		2,773,000			5,224,000
Regulatory Assets, Noncurrent	2,407,000		2,407,000			2,384,000
Regulatory Assets	5,180,000		5,180,000			7,608,000
Total regulatory assets, net of amortization [Member]
SCHEDULE OF REGULATED ASSETS AND LIABILITIES [Line Items]
Regulatory Assets, Current	71,748,000		71,748,000			47,440,000
Regulatory Assets, Noncurrent	364,117,000		364,117,000			391,036,000
Regulatory Assets	435,865,000		435,865,000			$ 438,476,000
Customer credit deferrals
SCHEDULE OF REGULATED ASSETS AND LIABILITIES [Line Items]
Regulatory Assets, Current	14,899,000		14,899,000
Regulatory Assets, Noncurrent	0		0
Regulatory Assets	$ 14,899,000		$ 14,899,000