SEGMENT REPORTING (Narrative) (Details)	6 Months Ended
	Dec. 31, 2017 segment item
Segment Reporting Information [Line Items]
Number of segments | segment	6
Fiber Solutions [Member] | Minimum
Segment Reporting Information [Line Items]
Number of dark fiber pairs leased to customers	2
Contract term	3 years
Fiber Solutions [Member] | Maximum
Segment Reporting Information [Line Items]
Number of dark fiber pairs leased to customers	12
Contract term	20 years
Transport [Member] | Minimum
Segment Reporting Information [Line Items]
Contract term	2 years
Transport [Member] | Maximum
Segment Reporting Information [Line Items]
Contract term	5 years
Enterprise Networks [Member] | Minimum
Segment Reporting Information [Line Items]
Contract term	1 year
Enterprise Networks [Member] | Maximum
Segment Reporting Information [Line Items]
Contract term	10 years
zColo [Member] | Minimum
Segment Reporting Information [Line Items]
Contract term	2 years
zColo [Member] | Maximum
Segment Reporting Information [Line Items]
Contract term	5 years
Other [Member]
Segment Reporting Information [Line Items]
Contract term	1 year