Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred tax assets:
Loan reserves	$ 300,538	$ 356,296
Stock-based compensation plans	10,174	10,914
Deferred revenue	1,318	1,441
Operating loss carryovers	394	83
Accrued expenses not currently deductible	14,307	13,139
Net unrealized losses	0	9,047
Unrecorded tax benefits	11,016	6,997
Other	1,097	1,003
Total deferred tax assets	338,844	398,920
Deferred tax liabilities:
Fixed assets	10,131	11,098
Acquired intangible assets	8,710	7,767
Market value adjustments on student loans, investments and derivatives	33	5,651
Net unrealized gains	6,459	0
Federal deferred for state receivable	1,921	7,456
Student loan premiums and discounts, net	12,396	11,336
Other	363	307
Total deferred tax liabilities	40,013	43,615
Net deferred tax assets	$ 298,831	$ 355,305