Borrowings (Details) (USD $)	Jun. 30, 2011	Dec. 31, 2010
Company's borrowings
Short-term borrowings	$ 30,765,693,000	$ 33,615,856,000
Long-term borrowings	160,765,277,000	163,543,504,000
Total	191,531,000,000	197,159,000,000
Unsecured Debt [Member]
Company's borrowings
Short-term borrowings	2,464,000,000	4,361,000,000
Long-term borrowings	16,787,000,000	15,742,000,000
Total	19,251,000,000	20,103,000,000
Brokered deposits [Member]
Company's borrowings
Short-term borrowings	1,550,000,000	1,387,000,000
Long-term borrowings	1,654,000,000	3,160,000,000
Total	3,204,000,000	4,547,000,000
Retail and other deposits [Member]
Company's borrowings
Short-term borrowings	1,487,000,000	1,370,000,000
Long-term borrowings	0	0
Total	1,487,000,000	1,370,000,000
Other Borrowings [Member]
Company's borrowings
Short-term borrowings	1,004,000,000	887,000,000
Long-term borrowings	0	0
Total	1,004,000,000	887,000,000
Subtotal unsecured borrowings [Member]
Company's borrowings
Short-term borrowings	6,505,000,000	8,005,000,000
Long-term borrowings	18,441,000,000	18,902,000,000
Total	24,946,000,000	26,907,000,000
FFELP Loans Securitizations [Member]
Company's borrowings
Short-term borrowings	0	0
Long-term borrowings	109,524,000,000	112,425,000,000
Total	109,524,000,000	112,425,000,000
Private Education Loans securitizations [Member]
Company's borrowings
Short-term borrowings	0	0
Long-term borrowings	21,815,000,000	21,409,000,000
Total	21,815,000,000	21,409,000,000
ED Conduit Program Facility [Member]
Company's borrowings
Short-term borrowings	22,756,000,000	24,484,000,000
Long-term borrowings	0	0
Total	22,756,000,000	24,484,000,000
ABCP Borrowings [Member]
Company's borrowings
Short-term borrowings	314,000,000	0
Long-term borrowings	5,000,000,000	5,853,000,000
Total	5,314,000,000	5,853,000,000
Acquisition Financing [Member]
Company's borrowings
Short-term borrowings	0	0
Long-term borrowings	1,010,000,000	1,064,000,000
Total	1,010,000,000	1,064,000,000
FHLB-DM Facility [Member]
Company's borrowings
Short-term borrowings	1,000,000,000	900,000,000
Long-term borrowings	0	0
Total	1,000,000,000	900,000,000
Indentured trusts [Member]
Company's borrowings
Short-term borrowings	0	0
Long-term borrowings	1,125,000,000	1,246,000,000
Total	1,125,000,000	1,246,000,000
Subtotal secured borrowings [Member]
Company's borrowings
Short-term borrowings	24,070,000,000	25,384,000,000
Long-term borrowings	138,474,000,000	141,997,000,000
Total	162,544,000,000	167,381,000,000
Total before hedge accounting adjustments [Member]
Company's borrowings
Short-term borrowings	30,575,000,000	33,389,000,000
Long-term borrowings	156,915,000,000	160,899,000,000
Total	187,490,000,000	194,288,000,000
Hedge accounting adjustments [Member]
Company's borrowings
Short-term borrowings	191,000,000	227,000,000
Long-term borrowings	3,850,000,000	2,644,000,000
Total	$ 4,041,000,000	$ 2,871,000,000