Borrowings (Details 1) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Securitization Activity
No. of Transactions	3	1	4	2
Loan Amount Securitized	$ 2,473,000,000	$ 1,211,000,000	$ 3,245,000,000	$ 3,140,000,000
Financing VIEs
Short-term borrowings	30,765,693,000		30,765,693,000		33,615,856,000
Long-term borrowings	160,765,277,000		160,765,277,000		163,543,504,000
Total	191,531,000,000		191,531,000,000		197,159,000,000
Loans	165,422,000,000		165,422,000,000		170,105,000,000
Cash	6,074,901,000		6,074,901,000		6,254,493,000
Other assets	10,129,933,000		10,129,933,000		8,970,272,000
Total Carrying Amount of Assets Securing Debt Outstanding	175,391,000,000		175,391,000,000		179,794,000,000
Private Education Loans [Member]
Securitization Activity
No. of Transactions	2		2	1
Loan Amount Securitized	1,699,000,000		1,699,000,000	1,929,000,000
FFELP Consolidation Loans [Member]
Securitization Activity
No. of Transactions	1		2
Loan Amount Securitized	774,000,000		1,546,000,000
FFELP Stafford/PLUS Loans [Member]
Securitization Activity
No. of Transactions		1		1
Loan Amount Securitized		1,211,000,000		1,211,000,000
Assets and liabilities of consolidated variable interest entities [Member] | ABCP Borrowings [Member]
Financing VIEs
Cash	77,000,000		77,000,000		94,000,000
Other assets	75,000,000		75,000,000		53,000,000
Assets and liabilities of consolidated variable interest entities [Member] | ABCP Borrowings [Member] | Secured Debt [Member]
Financing VIEs
Short-term borrowings	314,000,000		314,000,000		0
Long-term borrowings	5,000,000,000		5,000,000,000		5,853,000,000
Total	5,314,000,000		5,314,000,000		5,853,000,000
ABCP Borrowings [Member]
Financing VIEs
Loans	5,661,000,000		5,661,000,000		6,290,000,000
Total Carrying Amount of Assets Securing Debt Outstanding	5,813,000,000		5,813,000,000		6,437,000,000
Assets and liabilities of consolidated variable interest entities [Member] | ED Conduit Program Facility [Member]
Financing VIEs
Cash	647,000,000		647,000,000		819,000,000
Other assets	572,000,000		572,000,000		634,000,000
Assets and liabilities of consolidated variable interest entities [Member] | ED Conduit Program Facility [Member] | Secured Debt [Member]
Financing VIEs
Short-term borrowings	22,756,000,000		22,756,000,000		24,484,000,000
Long-term borrowings	0		0		0
Total	22,756,000,000		22,756,000,000		24,484,000,000
ED Conduit Program Facility [Member]
Financing VIEs
Loans	22,802,000,000		22,802,000,000		24,511,000,000
Total Carrying Amount of Assets Securing Debt Outstanding	24,021,000,000		24,021,000,000		25,964,000,000
Assets and liabilities of consolidated variable interest entities [Member]
Financing VIEs
Short-term borrowings	23,069,956,000		23,069,956,000		24,484,353,000
Long-term borrowings	139,877,694,000		139,877,694,000		142,243,771,000
Cash	5,846,002,000		5,846,002,000		5,983,080,000
Other assets	4,122,981,000		4,122,981,000		3,705,716,000
Assets and liabilities of consolidated variable interest entities [Member] | Secured Debt [Member]
Financing VIEs
Short-term borrowings	23,070,000,000		23,070,000,000		24,484,000,000
Long-term borrowings	139,878,000,000		139,878,000,000		142,244,000,000
Total	162,948,000,000		162,948,000,000		166,728,000,000
Assets and liabilities of consolidated variable interest entities [Member] | Secured Debt [Member] | FFELP Loans Securitizations [Member]
Financing VIEs
Short-term borrowings	0		0		0
Long-term borrowings	109,524,000,000		109,524,000,000		112,425,000,000
Total	109,524,000,000		109,524,000,000		112,425,000,000
Assets and liabilities of consolidated variable interest entities [Member] | Secured Debt [Member] | Private Education Loans securitizations [Member]
Financing VIEs
Short-term borrowings	0		0		0
Long-term borrowings	21,815,000,000		21,815,000,000		21,409,000,000
Total	21,815,000,000		21,815,000,000		21,409,000,000
Assets and liabilities of consolidated variable interest entities [Member] | Secured Debt [Member] | Indentured trusts [Member]
Financing VIEs
Short-term borrowings	0		0		0
Long-term borrowings	1,125,000,000		1,125,000,000		1,246,000,000
Total	1,125,000,000		1,125,000,000		1,246,000,000
Assets and liabilities of consolidated variable interest entities [Member] | Secured Debt [Member] | Total before hedge accounting adjustments [Member]
Financing VIEs
Short-term borrowings	23,070,000,000		23,070,000,000		24,484,000,000
Long-term borrowings	137,464,000,000		137,464,000,000		140,933,000,000
Total	160,534,000,000		160,534,000,000		165,417,000,000
Assets and liabilities of consolidated variable interest entities [Member] | Secured Debt [Member] | Hedge accounting adjustments [Member]
Financing VIEs
Short-term borrowings	0		0		0
Long-term borrowings	2,414,000,000		2,414,000,000		1,311,000,000
Total	2,414,000,000		2,414,000,000		1,311,000,000
Assets and liabilities of consolidated variable interest entities [Member] | FFELP Loans Securitizations [Member]
Financing VIEs
Cash	3,825,000,000		3,825,000,000		3,728,000,000
Other assets	575,000,000		575,000,000		966,000,000
Assets and liabilities of consolidated variable interest entities [Member] | Private Education Loans securitizations [Member]
Financing VIEs
Cash	1,171,000,000		1,171,000,000		1,213,000,000
Other assets	753,000,000		753,000,000		690,000,000
Assets and liabilities of consolidated variable interest entities [Member] | Indentured trusts [Member]
Financing VIEs
Cash	126,000,000		126,000,000		129,000,000
Other assets	13,000,000		13,000,000		15,000,000
Assets and liabilities of consolidated variable interest entities [Member] | Total before hedge accounting adjustments [Member]
Financing VIEs
Cash	5,846,000,000		5,846,000,000		5,983,000,000
Other assets	1,988,000,000		1,988,000,000		2,358,000,000
Assets and liabilities of consolidated variable interest entities [Member] | Hedge accounting adjustments [Member]
Financing VIEs
Cash	0		0		0
Other assets	2,135,000,000		2,135,000,000		1,348,000,000
FFELP Loans Securitizations [Member]
Financing VIEs
Loans	110,434,000,000		110,434,000,000		113,400,000,000
Total Carrying Amount of Assets Securing Debt Outstanding	114,834,000,000		114,834,000,000		118,094,000,000
Private Education Loans securitizations [Member]
Financing VIEs
Loans	25,084,000,000		25,084,000,000		24,355,000,000
Total Carrying Amount of Assets Securing Debt Outstanding	27,008,000,000		27,008,000,000		26,258,000,000
Indentured trusts [Member]
Financing VIEs
Loans	1,441,000,000		1,441,000,000		1,549,000,000
Total Carrying Amount of Assets Securing Debt Outstanding	1,580,000,000		1,580,000,000		1,693,000,000
Total before hedge accounting adjustments [Member]
Financing VIEs
Loans	165,422,000,000		165,422,000,000		170,105,000,000
Total Carrying Amount of Assets Securing Debt Outstanding	173,256,000,000		173,256,000,000		178,446,000,000
Hedge accounting adjustments [Member]
Financing VIEs
Loans	0		0		0
Total Carrying Amount of Assets Securing Debt Outstanding	$ 2,135,000,000		$ 2,135,000,000		$ 1,348,000,000