Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2024	Jun. 30, 2023	Dec. 31, 2020
Summary Of Significant Accounting Policies [Line Items]
Allowance for loans losses	$ 832	$ 1,022	$ 1,271			$ 1,377
Percentage of threshold	50.00%
Goodwill impaired method for fair value determination	We complete a goodwill impairment analysis which may be a qualitative or a quantitative analysis depending on the facts and circumstances associated with the reporting unit. In conjunction with a qualitative impairment analysis, we assess relevant qualitative factors to determine whether it is “more-likely-than-not” that the fair value of a reporting unit is less than its carrying amount. The “more-likely-than-not” threshold is defined as having a likelihood of more than 50%. If, based on first assessing impairment utilizing a qualitative approach, we determine it is “more-likely-than-not” that the fair value of the reporting unit is less than its carrying amount, we will also complete a quantitative impairment analysis. In conjunction with a quantitative impairment analysis, we compare the fair value of the reporting unit to the reporting unit’s carrying value, including goodwill. If the carrying value of the reporting unit exceeds the fair value, goodwill is impaired in an amount equal to the amount by which the carrying value exceeds the fair value of the reporting unit not to exceed the goodwill amount attributed to the reporting unit.
Option to exercise clean-up call and purchase education loans from trust of original loan balance	10% or less of the original loan balance
Percentage of trust's asset balance needed to trigger clean-up call	10.00%
Option to purchase education loan of the trust's initial pool balance	up to 10% of the trust’s initial pool balance
Assets	$ 61,375	70,795
Description of post employment benefits	The Company administers the Navient Corporation Employee Severance Plan and the Navient Corporation Executive Severance Plan for Senior Officers (collectively, the Severance Plan). The Severance Plan provides severance benefits in the event of termination of the Company’s full-time employees and part-time employees who work at least 24 hours per week.
Restructuring/other reorganization expenses	$ 25	36	26
Securitization Trust [Member]
Summary Of Significant Accounting Policies [Line Items]
Assets	11
FFELP Loans [Member]
Summary Of Significant Accounting Policies [Line Items]
Allowance for loans losses	$ 215	222	262			288
Loans Disbursed after October 1, 1993, and before July 1, 2006 [Member] | FFELP Loans [Member]
Summary Of Significant Accounting Policies [Line Items]
Percentage reimbursement on all qualifying default claims period	98.00%
Loans Disbursed on or after July 1, 2006 [Member] | FFELP Loans [Member]
Summary Of Significant Accounting Policies [Line Items]
Percentage reimbursement on all qualifying default claims period	97.00%
Loans Disbursed prior to October 1, 1993 [Member] | FFELP Loans [Member]
Summary Of Significant Accounting Policies [Line Items]
Percentage reimbursement on all qualifying default claims period	100.00%
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Percentage of aggregate education loan to purchase	10.00%
Private Education Loans [Member]
Summary Of Significant Accounting Policies [Line Items]
Allowance for loans losses	$ 617	800	$ 1,009			$ 1,089
Private Education Loans [Member] | Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Delinquency period (in days)	212 days
ASU 2022-02 [Member] | Interest Rate Concession [Member]
Summary Of Significant Accounting Policies [Line Items]
Allowance for loans losses	$ 77	$ 77
Allowance for loans losses released	$ 67
ASU 2022-02 [Member] | Interest Rate Concession [Member] | Forecast [Member]
Summary Of Significant Accounting Policies [Line Items]
Allowance for loans losses				$ 10
ASU 2020-04 [Member
Summary Of Significant Accounting Policies [Line Items]
Debt					$ 12,000