Accumulated Other Comprehensive Income (Loss) - Reclassification out of AOCI (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Feb. 28, 2021	Feb. 29, 2020	Feb. 28, 2021	Feb. 29, 2020
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Less: Tax effect	$ 8.0	$ 16.8	$ 7.6	$ 11.6
Net income (loss) attributable to Scholastic Corporation	13.9	43.3	18.6	30.8
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)	0.1	0.3	0.4	0.8
Amortization of prior service credit	(0.2)	0.0	(0.4)	(0.1)
Less: Tax effect	0.1	0.0	0.2	0.0
Net income (loss) attributable to Scholastic Corporation	$ 0.0	$ 0.3	$ 0.2	$ 0.7