GOVERNMENT GRANTS (Details) $ in Thousands		1 Months Ended	3 Months Ended			6 Months Ended		12 Months Ended		18 Months Ended
	Nov. 16, 2020 USD ($)	Sep. 30, 2021 USD ($)	Jun. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($) item	Jun. 30, 2020 USD ($)	Dec. 31, 2020 USD ($) item MW	Dec. 31, 2018 USD ($)	Jun. 30, 2021 USD ($)
Government Grants
Revenue			$ 123,865		$ 109,098	$ 248,375	$ 220,004
Payment for PALs							20,000
Universal Service Fund programs
Government Grants
Number of fund disbursement programs | item						4
High-Cost Support Program | Grant Reduction During First Year
Government Grants
Amount of reduction in grant amount awarded	$ 10,900
High-Cost Support Program | US Telecom
Government Grants
Revenue			300		300	$ 600	600
High-Cost Support Program | International Telecom
Government Grants
Revenue			4,300		4,100	8,400	8,200
High-Cost Support Program | International Telecom | Grant Reduction During First Year
Government Grants
Ratio of reduction in grant amount	0.67
High-Cost Support Program | International Telecom | Grant Reduction During Second Year
Government Grants
Ratio of reduction in grant amount	0.33
Amount of reduction in grant amount awarded	$ 5,500
E-Rate, Lifeline and Rural Health Care Support Programs
Government Grants
Revenue			1,800		2,200	3,900	4,400
Network Connectivity for Eligible Communities
Government Grants
Grant Funds Awarded						6,500		$ 16,800
Offsetting operating activities						1,300
Construction obligation completed		$ 10,200
Construction obligation yet to be completed		$ 13,100
CARES Act
Government Grants
Grant Funds Awarded						2,400		$ 16,300		$ 18,700
Grant funds used to offset fixed asset related costs			18,400			18,400				18,400
Grant funds used to offset operating expenses			300			300				$ 300
Tribal Bidding Credit
Government Grants
Wireless service spectrum (in Mhz) | MW								600
Revenue									$ 7,400
Grant funds used to offset fixed asset related costs								$ 6,100
Grant funds used to offset operating expenses								1,300
Offsetting operating activities			300			600
Amount spent on capital expenditure						6,100
Connect America Fund Phase II Auction
Government Grants
Revenue			$ 1,900		$ 1,900	$ 3,800	$ 3,800
Grant Funds Awarded									$ 79,900
Grant fund term									10 years
CBRS Auction
Government Grants
Initial term of licenses				10 years
Payment for PALs				$ 20,400
RDOF
Government Grants
Grant funds expected to be awarded								$ 20,100
Grant fund term								10 years
Number of households to receive broadband coverage | item								10,000