Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2024

Fair Value Disclosures [Abstract]

Valuation of Financial Instruments that are Marked-to-Market on Recurring Basis

The following table summarizes the valuation of our financial instruments that are marked-to-fair value on a recurring basis.

	Fair Value Measurements on a Recurring Basis
	March 31, 2024								December 31, 2023
(Dollars in thousands)	Level 1		Level 2		Level 3		Total		Level 1		Level 2		Level 3		Total
Assets:
Trading investments	$	—	$	—	$	58,166	$	58,166	$	—	$	—	$	54,481	$	54,481
Available-for-sale investments	—		2,271,108		—		2,271,108		—		2,411,622		—		2,411,622
Derivative instruments	—		208		—		208		—		—		—		—
Total	$	—	$	2,271,316	$	58,166	$	2,329,482	$	—	$	2,411,622	$	54,481	$	2,466,103
Liabilities:
Derivative instruments	$	—	$	(116)	$	—	$	(116)	$	—	$	(370)	$	—	$	(370)
Total	$	—	$	(116)	$	—	$	(116)	$	—	$	(370)	$	—	$	(370)

Fair Values of Financial Assets and Liabilities, Including Derivative Financial Instruments

The following table summarizes the fair values of our financial assets and liabilities, including derivative financial instruments.

	March 31, 2024						December 31, 2023
(Dollars in thousands)	Fair Value		Carrying Value		Difference		Fair Value		Carrying Value		Difference
Earning assets:
Loans held for investment, net:
Private Education Loans	$	22,342,438	$	19,687,783	$	2,654,655	$	22,229,045	$	19,772,293	$	2,456,752
FFELP Loans	521,527		513,006		8,521		542,775		534,064		8,711
Cash and cash equivalents	3,584,013		3,584,013		—		4,149,838		4,149,838		—
Trading investments	58,166		58,166		—		54,481		54,481		—
Available-for-sale investments	2,271,108		2,271,108		—		2,411,622		2,411,622		—
Accrued interest receivable	1,467,249		1,386,487		80,762		1,448,766		1,379,904		68,862
Tax indemnification receivable	—		—		—		—		—		—
Derivative instruments	208		208		—		—		—		—
Total earning assets	$	30,244,709	$	27,500,771	$	2,743,938	$	30,836,527	$	28,302,202	$	2,534,325
Interest-bearing liabilities:
Money-market and savings accounts	$	10,268,578	$	10,417,629	$	149,051	$	11,134,883	$	11,203,292	$	68,409
Certificates of deposit	10,431,342		10,483,580		52,238		10,380,684		10,448,365		67,681
Long-term borrowings	4,703,196		4,976,882		273,686		4,873,690		5,227,512		353,822
Accrued interest payable	89,328		89,328		—		105,066		105,066		—
Derivative instruments	116		116		—		370		370		—
Total interest-bearing liabilities	$	25,492,560	$	25,967,535	$	474,975	$	26,494,693	$	26,984,605	$	489,912
Excess of net asset fair value over carrying value					$	3,218,913					$	3,024,237