BASIS OF PREPARATION - Merger (Details) $ / shares in Units, $ in Thousands		3 Months Ended
	Mar. 11, 2018 USD ($) d $ / shares	Sep. 29, 2018 USD ($) $ / shares	Sep. 30, 2017 USD ($)	Jun. 30, 2018 $ / shares
Business Combination, Separately Recognized Transactions [Line Items]
Cash consideration paid per cancelled share of Oclaro stock (in USD per share) | $ / shares	$ 5.60
Common stock, par value (in usd per share) | $ / shares		$ 0.01		$ 0.01
Increase in cash consideration per share included in Exchange ratio if threshold shares attained (in USD per share) | $ / shares	$ 68.975
Trading Days Included in Average Closing Price | d	10
Amount payable if Oclaro terminates the Merger Agreement | $	$ 63,000
Amount receivable if Lumentum terminates the Merger Agreement | $	$ 80,000
Restructuring and acquisition-related expenses | $		$ 800	$ 0
Lumentum
Business Combination, Separately Recognized Transactions [Line Items]
Conversion ratio of new shares to Company shares	0.0636
Common stock, par value (in usd per share) | $ / shares	$ 0.001
Merger consideration shares as percent of total pre-merger shares that would trigger an increase of the purchase price per share (percent)	19.90%
Restructuring and Acquisition-related Expenses
Business Combination, Separately Recognized Transactions [Line Items]
Restructuring and acquisition-related expenses | $		$ 300