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Stock-Based Compensation Plans and Arrangements - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation cost	$ 47	$ 47	$ 56
Unrecognized compensation cost	19.00
Weighted average period for total unrecognized compensation cost	1 year 9 months 18 days
Offering period of employee stock purchase plan	12 months
Maximum contribution amount per employee to ESPP	$7,500 plus accrued interest
Shares of the company's common stock purchased by ESPP participants	218,389	192,755	278,266
SLM Corporation 2012 Omnibus Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Approval date	May 24, 2012
Shares authorized to be issued under plan	20,000,000
Grants Made Prior to 2012 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum term for stock options (in years)	10 years
Grants Made since 2012 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum term for stock options (in years)	5 years
Time Vested Stock Options [Member] | Management Employee [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	Vest over three years
Time Vested Stock Options [Member] | Non Management Employee [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	Vest over three years
Time Vested Stock Options [Member] | Non Employee Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	Vest upon the director's election to the Board
Performance-Vested Stock Options [Member] | Management Employee [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	Vest one-third per year for three years based on corporate earnings-related performance targets
Price Vested Stock Options [Member] | Management Employee [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	Vest upon our common stock reaching a targeted closing price for a set number of days
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Approval date	May 24, 2012
Shares authorized to be issued under plan	6,000,000
Unrecognized compensation cost	0.10
Vesting period	One-year
Percentage of discount available to employees under ESPP	15.00%
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost	$ 0.01
Weighted average period for total unrecognized compensation cost	1 month 6 days
Vesting period	Vest over three years and in some cases based on corporate earnings-related performance targets
Restricted Stock Units, RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	RSUs may be time-vested over three years or vested at grant but subject to transfer restrictions
Performance Stock Units, PSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	PSUs vest based on corporate earnings-related performance targets over a three-year period

X

- Definition

Total dollar amount that an employee can contribute to the company's employee stock purchase plan over the length of the offering period.

+ References

No definition available.

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X

- Definition

Contract life of employee stock option.

+ References

No definition available.

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X

- Definition

Number of months in which employees can contribute to the company's current employee stock purchase plan.

+ References

No definition available.

+ Details

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X

- Definition

Approval date of stock-based compensation plan or amendment.

+ References

No definition available.

+ Details

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X

- Definition

The vesting term over which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition.

+ References

No definition available.

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- Definition

Unrecognized cost of unvested share-based compensation awards.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (i)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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X

- Definition

Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

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- Definition

The aggregate amount of noncash, equity-based employee remuneration. This may include the value of stock or unit options, amortization of restricted stock or units, and adjustment for officers' compensation. As noncash, this element is an add back when calculating net cash generated by operating activities using the indirect method.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

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-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

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- Definition

Discount rate from fair value on offering date that participants pay for shares.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

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-Section 50

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- Definition

The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (a)(3)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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X

- Definition

The number of shares purchased on the open market during the period for issuance to employees under the plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901



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