Accumulated Other Comprehensive Income (Loss) - Reclassification out of AOCI (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Nov. 30, 2020	Nov. 30, 2019	Nov. 30, 2020	Nov. 30, 2019
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Less: Tax effect	$ (12.4)	$ (33.8)	$ (0.4)	$ (5.2)
Net income (loss) attributable to Scholastic Corporation	(35.1)	(71.0)	4.7	(12.5)
Amount reclassified from Accumulated other comprehensive income (loss) | Retirement benefit plans
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of unrecognized gain (loss)	0.2	0.3	0.3	0.5
Amortization of prior service credit	(0.2)	(0.1)	(0.2)	(0.1)
Less: Tax effect	0.1	0.0	0.1	0.0
Net income (loss) attributable to Scholastic Corporation	$ 0.1	$ 0.2	$ 0.2	$ 0.4