Accumulated Other Comprehensive Income (Loss) - Reclassification out of AOCI (Details) - USD ($) $ in Millions	3 Months Ended
	Aug. 31, 2020	Aug. 31, 2019
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Less: Tax effect	$ 12.0	$ 28.6
Net income (loss) attributable to Scholastic Corporation	39.8	58.5
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)	0.1	0.2
Amortization of prior service credit	0.0	0.0
Less: Tax effect	0.0	0.0
Net income (loss) attributable to Scholastic Corporation	$ 0.1	$ 0.2