CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - USD ($)	Total	Total SLM Corporation Equity	Preferred Stock	Treasury	Common Stock	Additional Paid-in Capital	Additional Paid-in Capital Navient’s Subsidiary Investment	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Non-controlling interest	Series A Preferred Stock	Series A Preferred Stock Total SLM Corporation Equity	Series A Preferred Stock Retained Earnings	Series B Preferred Stock	Series B Preferred Stock Total SLM Corporation Equity	Series B Preferred Stock Retained Earnings
Beginning balance, shares issued (in shares) at Dec. 31, 2013			0		0
Beginning balance (in shares) at Dec. 31, 2013				0	0
Beginning balance at Dec. 31, 2013	$ 1,166,143,000	$ 1,161,471,000	$ 0	$ 0	$ 0	$ 0	$ 1,164,495,000	$ (3,024,000)	$ 0	$ 4,672,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	193,785,000	194,219,000					68,173,000		126,046,000	(434,000)
Other comprehensive loss, net of tax	(8,369,000)	(8,369,000)						(8,369,000)
Total comprehensive income (loss)	185,416,000	185,850,000								(434,000)
Net transfers from affiliate	479,409,000	479,409,000					479,409,000
Separation adjustments related to Spin-Off of Navient Corporation (in shares)			7,300,000	0	422,790,320
Separation adjustments related to Spin-Off of Navient Corporation	0		$ 565,000,000		$ 84,558,000	1,062,519,000	(1,712,077,000)
Sale of non-controlling interest	(4,238,000)									(4,238,000)
Cash dividends:
Preferred stock											$ (7,667,000)	$ (7,667,000)	$ (7,667,000)	$ (5,266,000)	$ (5,266,000)	$ (5,266,000)
Dividend equivalent units related to employee stock-based compensation plans	$ 0					47,000			(47,000)
Issuance of common shares (in shares)	2,013,805				2,013,805
Issuance of common shares	$ 8,683,000	8,683,000			$ 403,000	8,280,000
Tax benefit (deficiency) related to employee stock-based compensation	3,271,000	3,271,000				3,271,000
Stock-based compensation expense	16,394,000	16,394,000				16,394,000
Shares repurchased related to employee stock-based compensation plans (in shares)				(1,365,277)	(1,365,277)
Shares repurchased related to employee stock-based compensation plans	(12,187,000)	(12,187,000)		$ (12,187,000)
Ending balance, shares issued (in shares) at Dec. 31, 2014			7,300,000		424,804,125
Ending balance (in shares) at Dec. 31, 2014				(1,365,277)	423,438,848
Ending balance at Dec. 31, 2014	1,829,958,000	1,829,958,000	$ 565,000,000	$ (12,187,000)	$ 84,961,000	1,090,511,000	$ 0	(11,393,000)	113,066,000	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	274,284,000	274,284,000							274,284,000
Other comprehensive loss, net of tax	(4,666,000)	(4,666,000)						(4,666,000)
Total comprehensive income (loss)	269,618,000	269,618,000
Net transfers from affiliate	$ 0
Separation adjustments related to Spin-Off of Navient Corporation		1,660,000				1,660,000
Cash dividends:
Preferred stock												(11,501,000)	(11,501,000)		(8,094,000)	(8,094,000)
Dividend equivalent units related to employee stock-based compensation plans		0				1,146,000			(1,146,000)
Issuance of common shares (in shares)	5,873,309				5,873,309
Issuance of common shares		15,980,000			$ 1,175,000	14,805,000
Tax benefit (deficiency) related to employee stock-based compensation		6,140,000				6,140,000
Stock-based compensation expense		21,598,000				21,598,000
Shares repurchased related to employee stock-based compensation plans (in shares)				(3,008,913)	(3,008,913)
Shares repurchased related to employee stock-based compensation plans		(29,036,000)		$ (29,036,000)
Ending balance, shares issued (in shares) at Dec. 31, 2015			7,300,000		430,677,434
Ending balance (in shares) at Dec. 31, 2015				(4,374,190)	426,303,244
Ending balance at Dec. 31, 2015	$ 2,096,323,000	2,096,323,000	$ 565,000,000	$ (41,223,000)	$ 86,136,000	1,135,860,000		(16,059,000)	366,609,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	250,327,000	250,327,000							250,327,000
Other comprehensive loss, net of tax	7,388,000	7,388,000						7,388,000
Total comprehensive income (loss)	$ 257,715,000	257,715,000
Cash dividends:
Preferred stock												$ (11,501,000)	$ (11,501,000)		$ (9,703,000)	$ (9,703,000)
Dividend equivalent units related to employee stock-based compensation plans		0				410,000			(410,000)
Issuance of common shares (in shares)	5,955,045				5,955,045
Issuance of common shares		19,191,000			$ 1,191,000	18,000,000
Tax benefit (deficiency) related to employee stock-based compensation		(1,650,000)				(1,650,000)
Stock-based compensation expense		22,944,000				22,944,000
Shares repurchased related to employee stock-based compensation plans (in shares)				(3,354,730)	(3,354,730)
Shares repurchased related to employee stock-based compensation plans		(26,261,000)		$ (26,261,000)
Ending balance, shares issued (in shares) at Dec. 31, 2016			7,300,000		436,632,479
Ending balance (in shares) at Dec. 31, 2016				(7,728,920)	428,903,559
Ending balance at Dec. 31, 2016	$ 2,347,058,000	$ 2,347,058,000	$ 565,000,000	$ (67,484,000)	$ 87,327,000	$ 1,175,564,000		$ (8,671,000)	$ 595,322,000