Accumulated Other Comprehensive Income (Loss) - Reclassification out of AOCI (Details) - USD ($) $ in Millions	3 Months Ended
	Aug. 31, 2019	Aug. 31, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of prior service credit	$ 0.0
Less: Tax effect	28.6	$ 22.1
Net income (loss) attributable to Scholastic Corporation	(58.5)	(61.3)
Retirement benefit plans
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of prior service credit	0.0
Amount reclassified from Accumulated other comprehensive income (loss) | Retirement benefit plans
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax	0.0	0.0
Amortization of unrecognized gain (loss)	0.2	0.2
Less: Tax effect	(0.0)	0.0
Net income (loss) attributable to Scholastic Corporation	$ (0.2)	$ (0.2)