Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2019

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
	December 31, 2019										December 31, 2018
	Level 1		Level 2			Level 3		Total			Level 1		Level 2			Level 3		Total
Assets
Available-for-sale investments	$	—	$	487,669		$	—	$	487,669		$	—	$	176,245		$	—	$	176,245
Derivative instruments	—		715			—		715			—		2,090			—		2,090
Total	$	—	$	488,384		$	—	$	488,384		$	—	$	178,335		$	—	$	178,335
Liabilities
Derivative instruments	$	—	$	(1,164	)	$	—	$	(1,164	)	$	—	$	(2,032	)	$	—	$	(2,032	)
Total	$	—	$	(1,164	)	$	—	$	(1,164	)	$	—	$	(2,032	)	$	—	$	(2,032	)

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.

	December 31, 2019							December 31, 2018
	Fair Value		Carrying Value		Difference			Fair Value		Carrying Value		Difference
Earning assets:
Loans held for investment, net:
Private Education Loans	$	24,988,941	$	22,896,515	$	2,092,426		$	22,313,419	$	20,294,843	$	2,018,576
FFELP Loans	795,055		783,816		11,239			859,185		847,889		11,296
Personal Loans	1,047,119		983,643		63,476			1,156,531		1,128,187		28,344
Credit Cards	3,818		3,818		—			—		—		—
Cash and cash equivalents	5,563,877		5,563,877		—			2,559,106		2,559,106		—
Available-for-sale investments	487,669		487,669		—			176,245		176,245		—
Accrued interest receivable	1,491,471		1,392,725		98,746			1,285,842		1,191,981		93,861
Tax indemnification receivable	27,558		27,558		—			39,207		39,207		—
Derivative instruments	715		715		—			2,090		2,090		—
Total earning assets	$	34,406,223	$	32,140,336	$	2,265,887		$	28,391,625	$	26,239,548	$	2,152,077
Interest-bearing liabilities:
Money-market and savings accounts	$	10,363,691	$	10,335,163	$	(28,528	)	$	9,370,957	$	9,390,108	$	19,151
Certificates of deposit	14,065,007		13,947,743		(117,264		)	9,513,194		9,551,974		38,780
Short-term borrowings	289,230		289,230		—			—		—		—
Long-term borrowings	4,434,323		4,354,037		(80,286		)	4,278,931		4,284,304		5,373
Accrued interest payable	75,158		75,158		—			61,341		61,341		—
Derivative instruments	1,164		1,164		—			2,032		2,032		—
Total interest-bearing liabilities	$	29,228,573	$	29,002,495	$	(226,078	)	$	23,226,455	$	23,289,759	$	63,304
Excess of net asset fair value over carrying value					$	2,039,809						$	2,215,381