Discontinued Operations - Summary of Amounts Included in Discontinued Operations (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Loss from discontinued operations, net of tax	$ (2,955)	$ (7,947)
HMH Books & Media segment [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Net sales	42,706	38,082
Costs	37,615	36,373
Amortization	1,395	1,885
Interest expense	6,557	7,530
Loss from discontinued operations before taxes	(2,861)	(7,706)
Income tax expense	(94)	(241)
Loss from discontinued operations, net of tax	$ (2,955)	$ (7,947)