Shareholders' Equity - Amounts Reclassified from Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Cost of Goods and Services Sold	$ 2,443.0	$ 2,594.0
Total before tax effect	242.0	96.0
Tax benefit on amounts reclassified into earnings	(61.0)	(22.0)
Net income attributable to Amcor plc	198.0	66.0
Amortization of prior service credit | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Cost of Goods and Services Sold	0.0	(1.0)
Amortization of actuarial loss | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Cost of Goods and Services Sold	2.0	2.0
Accumulated Defined Benefit Plans Adjustments | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Total before tax effect	2.0	1.0
Tax benefit on amounts reclassified into earnings	1.0	0.0
Net income attributable to Amcor plc	3.0	1.0
(Gains) losses on cash flow hedges | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Total before tax effect	4.0	2.0
Tax benefit on amounts reclassified into earnings	0.0	0.0
Net income attributable to Amcor plc	4.0	2.0
(Gains) losses on cash flow hedges | Reclassification out of Accumulated Other Comprehensive Income [Member] | Commodity contracts
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Cost of Goods and Services Sold	3.0	2.0
(Gains) losses on cash flow hedges | Reclassification out of Accumulated Other Comprehensive Income [Member] | Treasury locks
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Cost of Goods and Services Sold	1.0	0.0
(Gains) losses on foreign currency translation | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Cost of Goods and Services Sold	25.0	9.0
Total before tax effect	25.0	9.0
Tax benefit on amounts reclassified into earnings	0.0	0.0
Net income attributable to Amcor plc	$ 25.0	$ 9.0