Allowance as a percentage of the ending total loan balance.

No definition available.

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- Definition

Allowance as a percentage of ending loans in repayment.

+ References

No definition available.

+ Details

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- Definition

Loans acquired unpaid principal balance.

+ References

No definition available.

+ Details

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Period Type:	instant

- Definition

Net adjustment from change in charge off rate.

+ References

No definition available.

+ Details

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- Definition

Portion of loan amount charged off at default.

+ References

No definition available.

+ Details

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Definition

Amount of addition to allowance reserve for credit loss arising from purchase of loan and lease portfolios.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7(d))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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Balance Type:	credit
Period Type:	duration

- Definition

Disclosure of the unamortized amount of the discount on the note or receivable which is deducted from the face amount of the receivable or loan. The discount or premium is the difference between the present value and the face amount.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28541-108399

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- Details

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Allowance for Loan Losses - Allowance for Credit Losses and Recorded Investments in Loans (Parenthetical) (Detail) - USD ($)	3 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jun. 01, 2017
Accounts Notes And Loans Receivable [Line Items]
Net adjustment resulting from the change in the charge-off rate				$ 330,000,000
JPM Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans purchased, Unpaid principal amount		$ 6,500,000,000
FFELP Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans purchased, Unpaid principal amount		5,700,000,000	$ 3,600,000,000	$ 3,700,000,000
Allowance for loans acquired		0
Loans receivable, discount		$ 43,000,000			$ 47,000,000
Allowance as a percentage of the ending total loan balance		0.07%	0.08%	0.08%
Allowance as a percentage of the ending loans in repayment		0.09%	0.09%	0.11%
FFELP Loans [Member] \| Loans Receivable Excluding Recent Loans Acquired [Member]
Accounts Notes And Loans Receivable [Line Items]
Allowance as a percentage of the ending total loan balance		0.08%
Allowance as a percentage of the ending loans in repayment		0.09%
FFELP Loans [Member] \| JPM Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans purchased, Unpaid principal amount		$ 3,500,000,000
Private Education Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Allowance for loans acquired		0
Loans receivable, discount		$ 392,000,000			$ 424,000,000
Allowance as a percentage of the ending total loan balance		5.06%	5.37%	5.18%
Allowance as a percentage of the ending loans in repayment		5.66%	6.10%	6.00%
Net adjustment resulting from the change in the charge-off rate				$ 330,000,000
Private Education Loans [Member] \| Minimum [Member]
Accounts Notes And Loans Receivable [Line Items]
Portion of loan amount charged off at default	73.00%			73.00%
Private Education Loans [Member] \| Maximum [Member]
Accounts Notes And Loans Receivable [Line Items]
Portion of loan amount charged off at default	79.00%			79.00%
Private Education Loans [Member] \| Loans Receivable Excluding Recent Loans Acquired [Member]
Accounts Notes And Loans Receivable [Line Items]
Allowance as a percentage of the ending total loan balance		5.69%
Allowance as a percentage of the ending loans in repayment		6.42%
Private Education Loans [Member] \| Loans Receivable For Partially Charged Off Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Net adjustment resulting from the change in the charge-off rate	$ 330,000,000			$ 330,000,000
Private Education Loans [Member] \| JPM Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans purchased, Unpaid principal amount		$ 3,000,000,000