Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2023

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, 2023								December 31, 2022
(Dollars in thousands)	Level 1		Level 2		Level 3		Total		Level 1		Level 2		Level 3		Total
Assets:
Trading investments	$	—	$	—	$	51,342	$	51,342	$	—	$	—	$	55,903	$	55,903
Available-for-sale investments	—		2,311,062		—		2,311,062		—		2,342,089		—		2,342,089
Derivative instruments	—		—		—		—		—		972		—		972
Total	$	—	$	2,311,062	$	51,342	$	2,362,404	$	—	$	2,343,061	$	55,903	$	2,398,964
Liabilities:
Derivative instruments	$	—	$	(1,815)	$	—	$	(1,815)	$	—	$	(567)	$	—	$	(567)
Total	$	—	$	(1,815)	$	—	$	(1,815)	$	—	$	(567)	$	—	$	(567)

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, 2023						December 31, 2022
(Dollars in thousands)	Fair Value		Carrying Value		Difference		Fair Value		Carrying Value		Difference
Earning assets:
Loans held for investment, net:
Private Education Loans	$	23,088,030	$	20,497,675	$	2,590,355	$	21,062,548	$	19,019,713	$	2,042,835
FFELP Loans	601,203		589,888		11,315		618,186		607,155		11,031
Loans held for sale	26,202		26,202		—		29,448		29,448		—
Cash and cash equivalents	3,716,379		3,716,379		—		4,616,117		4,616,117		—
Trading investments	51,342		51,342		—		55,903		55,903		—
Available-for-sale investments	2,311,062		2,311,062		—		2,342,089		2,342,089		—
Accrued interest receivable	1,393,556		1,331,017		62,539		1,237,074		1,202,059		35,015
Tax indemnification receivable	2,858		2,858		—		2,816		2,816		—
Derivative instruments	—		—		—		972		972		—
Total earning assets	$	31,190,632	$	28,526,423	$	2,664,209	$	29,965,153	$	27,876,272	$	2,088,881
Interest-bearing liabilities:
Money-market and savings accounts	$	11,671,878	$	11,796,120	$	124,242	$	11,854,849	$	11,959,828	$	104,979
Certificates of deposit	9,637,370		10,005,546		368,176		9,175,339		9,486,819		311,480
Long-term borrowings	5,106,299		5,513,976		407,677		4,813,233		5,235,114		421,881
Accrued interest payable	91,943		91,943		—		71,586		71,586		—
Derivative instruments	1,815		1,815		—		567		567		—
Total interest-bearing liabilities	$	26,509,305	$	27,409,400	$	900,095	$	25,915,574	$	26,753,914	$	838,340
Excess of net asset fair value over carrying value					$	3,564,304					$	2,927,221