Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Cash flows from operating activities
Net income	$ 255	$ 370
Adjustments to reconcile net income to net cash (used in) provided by operating activities:
(Gains) on sales of education loans		(76)
Goodwill and acquired intangible asset impairment and amortization expense	4	5
Stock-based compensation expense	9	10
Mark-to-market (gains) losses on derivative and hedging activities, net	(314)	(198)
Provisions for loan losses	16	(87)
Decrease in accrued interest receivable	48	80
(Decrease) in accrued interest payable	(15)	(45)
Decrease in other assets	174	111
(Decrease) increase in other liabilities	(286)	9
Total adjustments	(364)	(191)
Net cash (used in) provided by operating activities	(109)	179
Cash flows from investing activities
Education loans originated and acquired	(1,091)	(1,734)
Proceeds from payments on education loans	2,789	3,009
Proceeds from sales of education loans		1,588
Other investing activities, net	53	22
Net cash provided by investing activities	1,751	2,885
Cash flows from financing activities
Borrowings collateralized by loans in trust - issued	995	1,828
Borrowings collateralized by loans in trust - repaid	(3,296)	(2,846)
Long-term unsecured notes issued		495
Long-term unsecured notes repaid		(78)
Other financing activities, net	43	(34)
Common stock repurchased	(115)	(100)
Common dividends paid	(24)	(29)
Net cash used in financing activities	(2,006)	(2,499)
Net (decrease) increase in cash, cash equivalents, restricted cash and restricted cash equivalents	(364)	565
Cash, cash equivalents, restricted cash and restricted cash equivalents at beginning of period	3,578	3,537
Cash, cash equivalents, restricted cash and restricted cash equivalents at end of period	3,214	4,102
Supplemental disclosure of cash flow information:
Interest paid	300	362
Income taxes paid	5	1
Income taxes refunds received	(4)
Noncash activity:
Investing activity - Held-to-maturity asset backed securities retained related to sales of education loans		53
Operating activity - Servicing assets recognized upon sales of education loans		20
Reconciliation of the Consolidated Statements of Cash Flows to the Consolidated Balance Sheets:
Cash and cash equivalents	708	1,497
Restricted cash and restricted cash equivalents	2,506	2,605
Total cash, cash equivalents, restricted cash and restricted cash equivalents at end of period	3,214	4,102
Asset-backed Securities, Securitized Loans and Receivables [Member]
Cash flows from financing activities
Asset-backed commercial paper conduits, net	$ 391	$ (1,735)