CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (USD $) In Thousands, except Share data, unless otherwise specified		Total		Preferred Stock	Common Stock	Treasury Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Total SLM Corporation Equity	Non-controlling interest	Series A Preferred Stock	Series A Preferred Stock Retained Earnings	Series A Preferred Stock Total SLM Corporation Equity	Series B Preferred Stock	Series B Preferred Stock Retained Earnings	Series B Preferred Stock Total SLM Corporation Equity	Navient's subsidiary investment Additional Paid-In Capital
Beginning Balance, value at Dec. 31, 2012		$ 1,089,301					$ 1,068,928	$ 14,348		$ 1,083,276	$ 6,025
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		197,723					198,743			198,743	(1,020)
Other comprehensive income (loss), net of tax		25,687						25,687		25,687
Comprehensive income		223,410								224,430	(1,020)
Net transfers (to) from affiliate		(139,539)					(139,539)			(139,539)
Cash dividends:
Issuance of common shares, shares	[1]	8,600,008
Ending Balance, value at Sep. 30, 2013		1,173,172					1,128,132	40,035		1,168,167	5,005
Beginning Balance, value at Jun. 30, 2013		1,205,950					1,162,822	37,790		1,200,612	5,338
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		49,057					49,390			49,390	(333)
Other comprehensive income (loss), net of tax		2,245						2,245		2,245
Comprehensive income		51,302								51,635	(333)
Net transfers (to) from affiliate		(84,080)					(84,080)			(84,080)
Cash dividends:
Issuance of common shares, shares	[1]	326,789
Ending Balance, value at Sep. 30, 2013		1,173,172					1,128,132	40,035		1,168,167	5,005
Beginning Balance, value at Dec. 31, 2013		1,166,143		0	0	0	0	(3,024)	0	1,161,471	4,672							1,164,495
Beginning Balance, shares at Dec. 31, 2013				0	0	0
Beginning Balances, shares issued at Dec. 31, 2013					0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		174,068					0		106,329	174,502	(434)							68,173
Other comprehensive income (loss), net of tax		1,172						1,172		1,172
Comprehensive income		175,240								175,674	(434)
Net transfers (to) from affiliate		479,409								479,409								479,409
Separation adjustments related to Spin-Off of Navient Corporation, shares				7,300,000	422,790,320
Separation adjustments related to Spin-Off of Navient Corporation		0		565,000	84,558		1,062,519			0								(1,712,077)
Sale of non-controlling interest		(4,238)									(4,238)
Cash dividends:
Cash dividends, preferred stock												(4,792)	(4,792)	(4,792)	(3,286)	(3,286)	(3,286)
Dividend equivalent units related to employee stock-based compensation plans							41		(41)
Issuance of common shares, shares		1,089,716	[1]		1,089,716
Issuance of common shares		4,610			219		4,391			4,610
Stock-based compensation expense		11,550					11,550			11,550
Shares repurchased related to employee stock-based compensation plans, shares					(715,393)	(715,393)
Shares repurchased related to employee stock-based compensation plans		(6,208)				(6,208)				(6,208)
Ending Balance, value at Sep. 30, 2014		1,818,428		565,000	84,777	(6,208)	1,078,501	(1,852)	98,210	1,818,428	0							0
Ending Balance, shares at Sep. 30, 2014				7,300,000	423,164,643	715,393
Ending Balance, shares issued at Sep. 30, 2014					423,880,036
Beginning Balance, value at Jun. 30, 2014		1,738,264		565,000	84,659	(3,113)	1,071,916	(365)	20,167	1,738,264	0							0
Beginning Balance, shares at Jun. 30, 2014				7,300,000	422,936,478	358,771
Beginning Balances, shares issued at Jun. 30, 2014					423,295,249
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		82,926							82,926	82,926
Other comprehensive income (loss), net of tax		(1,487)						(1,487)		(1,487)
Comprehensive income		81,439								81,439
Net transfers (to) from affiliate		0
Cash dividends:
Cash dividends, preferred stock												(2,875)	(2,875)	(2,875)	(1,975)	(1,975)	(1,975)
Dividend equivalent units related to employee stock-based compensation plans							33		(33)
Issuance of common shares, shares		584,787	[1]		584,787
Issuance of common shares		2,165			118		2,047			2,165
Stock-based compensation expense		4,505					4,505			4,505
Shares repurchased related to employee stock-based compensation plans, shares					(356,622)	(356,622)
Shares repurchased related to employee stock-based compensation plans		(3,095)				(3,095)				(3,095)
Ending Balance, value at Sep. 30, 2014		$ 1,818,428			$ 84,777	$ (6,208)	$ 1,078,501	$ (1,852)	$ 98,210	$ 1,818,428
Ending Balance, shares at Sep. 30, 2014					423,164,643	715,393
Ending Balance, shares issued at Sep. 30, 2014					423,880,036

[1] Common shares issued under our various compensation and benefit plans.