Segment Information - Summary of Consolidated Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Assets:
Total Assets	$ 723,187	$ 371,018
Corporate and Other
Assets:
Total Assets	109,262	210,083
APUS Segment | Operating Segments
Assets:
Total Assets	128,331	112,461
RU Segment | Operating Segments
Assets:
Total Assets	432,767	0
HCN Segment | Operating Segments
Assets:
Total Assets	$ 52,827	$ 48,474