Accumulated Other Comprehensive Income (Loss) - Reclassification out of AOCI (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Feb. 29, 2020	Nov. 30, 2019	Aug. 31, 2019	Feb. 28, 2019	Nov. 30, 2018	Aug. 31, 2018	Feb. 29, 2020	Feb. 28, 2019
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Less: Tax effect	$ 16.8			$ 8.2			$ 11.6	$ 3.5
Net income (loss) attributable to Scholastic Corporation	43.3	$ (71.0)	$ 58.5	12.6	$ (71.6)	$ 61.3	30.8	2.3
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			0.8	0.6
Amortization of prior service credit	0.0			0.0			(0.1)	(0.1)
Less: Tax effect	(0.0)			(0.0)			(0.0)	(0.0)
Net income (loss) attributable to Scholastic Corporation	$ 0.3			$ 0.2			$ 0.7	$ 0.5