Allocation methodology description.

No definition available.

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- Definition

A description of the remaining amortization period of the company's FFELP loan portfolio.

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No definition available.

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Amortization period weighted average life.

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No definition available.

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- Definition

Loans acquired unpaid principal balance.

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No definition available.

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- Definition

Loans under service contract.

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No definition available.

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- Definition

Number of borrowers helped to successfully rehabilitate loans.

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No definition available.

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- Definition

Number of clients for business processing services.

+ References

No definition available.

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- Definition

Number of service contract accounts.

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No definition available.

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- Definition

Number of years experience.

+ References

No definition available.

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- Definition

The percentage of a FFELP loan's principal and accrued interest covered by guarantees.

+ References

No definition available.

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- Definition

Percentage of loans funded through securitization debt.

+ References

No definition available.

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- Definition

Private education refinance loans originated.

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No definition available.

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- Definition

Servicing contract revenue.

+ References

No definition available.

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- Definition

For an unclassified balance sheet, the amount due from customers or clients for goods or services that have been delivered or sold in the normal course of business, reduced to their estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 210
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- Definition

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Amount of revenue recognized that was previously reported as deferred or unearned revenue.

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- Definition

Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes loans held for sale. Excludes loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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- Definition

Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

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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.

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Amount of revenue from servicing real estate mortgages, credit cards, and other financial assets held by others. Includes premiums received in lieu of regular servicing fees.

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Segment Reporting - Additional Information (Detail) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2017 USD ($) Segment	Sep. 30, 2017 USD ($)	Dec. 31, 2017 USD ($) Account Borrower Client	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Segment Reporting Information [Line Items]
Number of reportable operating segments \| Segment	4
Loans, net	$ 105,122		$ 105,122	$ 111,070
Servicing revenue			$ 290	304	$ 340
Number of clients for business processing services \| Client			600
Accounts receivable	108		$ 108	95
Total assets	114,991		$ 114,991	121,136
Default Aversion Service [Member]
Segment Reporting Information [Line Items]
Deferred asset recovery revenue recognized		$ 47
Minimum [Member]
Segment Reporting Information [Line Items]
Number of borrowers helped to successfully rehabilitate loans \| Borrower			261,000
Great Lakes [Member]
Segment Reporting Information [Line Items]
Servicing revenue			$ 238	172
Great Lakes [Member] \| Default Aversion Service [Member]
Segment Reporting Information [Line Items]
Deferred asset recovery revenue recognized			47
Consumer Lending Segment [Member]
Segment Reporting Information [Line Items]
Loans, net	23,419		$ 23,419	23,340
Number of years experience			40 years
Total assets	25,268		$ 25,268	25,569
Business Processing [Member]
Segment Reporting Information [Line Items]
Total assets	466		466	373
Business Processing [Member] \| Nonfederal Education Loan [Member]
Segment Reporting Information [Line Items]
Accounts receivable	11,400		11,400	10,100	9,900
Other Segment [Member]
Segment Reporting Information [Line Items]
Total assets	2,100		$ 2,100	1,900
Department of Education [Member] \| Federal Education Loans [Member]
Segment Reporting Information [Line Items]
Number of contracts under ED servicing contract \| Account			6,100,000
Loans under service contract	205,900		$ 205,900
Revenue from servicing contract			150
Earnest [Member] \| Consumer Lending Segment [Member]
Segment Reporting Information [Line Items]
Private education refinance loans originated			900
Private Education Refinance Loan [Member] \| Consumer Lending Segment [Member]
Segment Reporting Information [Line Items]
Loans, net	761		761
Private Education Loans [Member]
Segment Reporting Information [Line Items]
Loans, net	23,419		23,419	23,340
Private Education Loans [Member] \| Consumer Lending Segment [Member]
Segment Reporting Information [Line Items]
Loans, net	$ 23,400		$ 23,400
Loan portfolio amortization period weighted average life			20 years
Amortization period			6 years
Percentage of loans funded through securitization debt	55.00%		55.00%
ED Asset Recovery and Servicing Contracts [Member]
Segment Reporting Information [Line Items]
Allocation methodology description			Since 2009, Navient has been one of four TIVAS that provides loan servicing for federal loans owned by ED. We continually strive to help our customers successfully navigate the repayment of their loans. Under the contract, we seek to improve on the performance metrics that determine the allocation of new accounts under the servicing contract with ED
FFELP Loans [Member]
Segment Reporting Information [Line Items]
Loans, net	$ 81,703		$ 81,703	87,730
Loan portfolio amortization period weighted average life			20 years
Amortization period			7 years
Loans purchased, unpaid principal amount	$ 5,700		$ 5,700	$ 3,600	$ 3,700
Percentage of general guaranty agreements of FFELP loans			97.00%
Percentage of loans funded through securitization debt	84.00%		84.00%