CONSOLIDATED STATEMENTS OF INCOME (Unaudited) - USD ($) shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Interest income:
Loans	$ 446,040,000	$ 430,099,000	$ 904,084,000	$ 861,903,000
Investments	8,513,000	3,168,000	13,992,000	5,896,000
Cash and cash equivalents	8,478,000	1,423,000	9,993,000	3,049,000
Total interest income	463,031,000	434,690,000	928,069,000	870,848,000
Interest expense:
Deposits	60,468,000	57,256,000	110,005,000	123,854,000
Interest expense on short-term borrowings	2,973,000	5,700,000	5,848,000	8,902,000
Interest expense on long-term borrowings	36,782,000	32,950,000	74,376,000	68,194,000
Total interest expense	100,223,000	95,906,000	190,229,000	200,950,000
Net interest income	362,808,000	338,784,000	737,840,000	669,898,000
Less: provisions for credit losses	30,545,000	69,677,000	128,595,000	(156,090,000)
Net interest income after provisions for credit losses	332,263,000	269,107,000	609,245,000	825,988,000
Non-interest income:
Gains on sales of loans, net	239,997,000	3,679,000	249,878,000	402,790,000
Gains (losses) on derivatives and hedging activities, net	0	89,000	(5,000)	117,000
Other income	18,256,000	48,580,000	30,305,000	62,868,000
Total non-interest income	258,253,000	52,348,000	280,178,000	465,775,000
Operating expenses:
Compensation and benefits	66,011,000	62,616,000	137,992,000	134,197,000
FDIC assessment fees	1,225,000	5,925,000	6,909,000	11,113,000
Other operating expenses	64,494,000	59,469,000	118,835,000	107,199,000
Total operating expenses	131,730,000	128,010,000	263,736,000	252,509,000
Acquired intangible assets amortization expense	2,417,000	0	3,150,000	0
Restructuring expenses	0	70,000	0	1,147,000
Total non-interest expenses	134,147,000	128,080,000	266,886,000	253,656,000
Income before income tax expense	456,369,000	193,375,000	622,537,000	1,038,107,000
Income tax expense	114,296,000	53,174,000	151,652,000	256,699,000
Net income	342,073,000	140,201,000	470,885,000	781,408,000
Preferred stock dividends	1,757,000	1,192,000	3,032,000	2,393,000
Net income attributable to SLM Corporation common stock	$ 340,316,000	$ 139,009,000	$ 467,853,000	$ 779,015,000
Basic earnings per common share (in dollars per share)	$ 1.30	$ 0.45	$ 1.74	$ 2.32
Average common shares outstanding (in shares)	261,333	312,183	269,112	336,478
Diluted earnings per common share (in dollars per share)	$ 1.29	$ 0.44	$ 1.72	$ 2.28
Average common and common equivalent shares outstanding (in shares)	264,122	317,119	272,343	341,544
Declared dividends per common share (in dollars per share)	$ 0.11	$ 0.03	$ 0.22	$ 0.06