CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Interest income:
Loans	$ 430,099	$ 480,170	$ 861,903	$ 1,035,447
Investments	3,168	3,096	5,896	5,759
Cash and cash equivalents	1,423	1,529	3,049	18,522
Total interest income	434,690	484,795	870,848	1,059,728
Interest expense:
Deposits	57,256	100,246	123,854	235,358
Interest expense on short-term borrowings	5,700	3,399	8,902	7,616
Interest expense on long-term borrowings	32,950	32,375	68,194	67,863
Total interest expense	95,906	136,020	200,950	310,837
Net interest income	338,784	348,775	669,898	748,891
Less: provisions for credit losses	69,677	351,887	(156,090)	413,145
Net interest income (loss) after provisions for credit losses	269,107	(3,112)	825,988	335,746
Non-interest income:
Gains (losses) on sales of loans, net	3,679	(369)	402,790	238,566
Gains on derivatives and hedging activities, net	89	3,751	117	49,423
Other income	48,580	25,412	62,868	32,899
Total non-interest income	52,348	28,794	465,775	320,888
Operating expenses
Compensation and benefits	62,616	72,448	134,197	156,670
FDIC assessment fees	5,925	7,163	11,113	16,053
Other operating expenses	59,469	61,946	107,199	116,132
Total operating expenses	128,010	141,557	252,509	288,855
Restructuring expenses	70	0	1,147	0
Total non-interest expenses	128,080	141,557	253,656	288,855
Income (loss) before income tax expense (benefit)	193,375	(115,875)	1,038,107	367,779
Income tax expense (benefit)	53,174	(30,664)	256,699	90,817
Net income (loss)	140,201	(85,211)	781,408	276,962
Preferred stock dividends	1,192	2,478	2,393	5,942
Net income (loss) attributable to SLM Corporation common stock	139,009	(87,689)	779,015	271,020
Net income (loss) attributable to SLM Corporation common stock	$ 139,009	$ (87,689)	$ 779,015	$ 271,020
Basic earnings (loss) per common share attributable to SLM Corporation (in dollars per share)	$ 0.45	$ (0.23)	$ 2.32	$ 0.69
Average common shares outstanding (in shares)	312,183,000	375,009,000	336,478,000	392,397,000
Diluted earnings (loss) per common share attributable to SLM Corporation (in dollars per share)	$ 0.44	$ (0.23)	$ 2.28	$ 0.69
Average common and common equivalent shares outstanding (in shares)	317,119,000	375,009,000	341,544,000	395,191,000
Declared dividends per common share attributable to SLM Corporation (in dollars per share)	$ 0.03	$ 0.06	$ 0.06	$ 0.09