Property and Equipment - Narrative (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Assets held for sale	$ 0	$ 2,100
Property and equipment, net	92,374	97,687
Loss on disposals of long-lived assets	2,093	5,970	$ 817
Depreciation expense	18,178	18,674	19,626
Amortization expense related to other assets	$ 598	710	$ 894
Software development | APEI Segment
Property, Plant and Equipment [Line Items]
Property and equipment, net		4,000
Incurred cost of long-lived assets disposed		$ 4,000