Accumulated Other Comprehensive Income (Loss) - Reclassification out of AOCI (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Nov. 30, 2019	Aug. 31, 2019	Nov. 30, 2018	Aug. 31, 2018	Nov. 30, 2019	Nov. 30, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Less: Tax effect	$ (33.8)		$ (26.8)		$ (5.2)	$ (4.7)
Net income (loss) attributable to Scholastic Corporation	(71.0)	$ 58.5	(71.6)	$ 61.3	(12.5)	(10.3)
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)	0.3		0.2		0.5	0.4
Amortization of prior service credit	(0.1)		(0.1)		(0.1)	(0.1)
Less: Tax effect	(0.0)		(0.0)		(0.0)	(0.0)
Net income (loss) attributable to Scholastic Corporation	$ 0.2		$ 0.1		$ 0.4	$ 0.3