Loans In Repayment And Percentage Of Each Status [Abstract]

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- Definition

Loans receivable for partially charged-off loans.

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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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- Definition

Percentage of financing receivable balance that is past due.

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Financing receivables that are current.

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- Definition

Recorded Investment in financing receivables that are past due at the balance sheet date.

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- Definition

Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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Amount, before allowance and fees, of loans and leases receivable. Excludes loans and leases covered under loss sharing agreements.

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Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

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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.

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Net amount of the investment in a contractual right to receive money on demand or on fixed or determinable dates that is recognized as an asset in the creditor's statement of financial position. Examples include, but are not limited to, credit card receivables, notes receivable and receivables relating to lessor's rights to payments from leases other than operating leases that have been recorded as assets. Excludes trade accounts receivable with contractual maturity of one year or less and arose from the sale of goods or services.

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Amount of deferred fees paid by borrowers and unamortized costs incurred to originate loans and leases, unamortized loan commitments and loan syndication fees, and premiums over or discounts from face amounts of loans that are being amortized into income as an adjustment to yield. Excludes amounts for loans and leases covered under loss sharing agreements.

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Allowance for Loan Losses - Age Analysis of Past Due Loans Delinquencies (Detail) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2019	Dec. 31, 2018	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017
Loans in repayment and percentage of each status:
Loans allowance for losses	$ (1,218)	$ (1,286)	$ (1,252)	$ (1,389)	$ (1,367)	$ (1,367)
FFELP Loans [Member]
Loans in repayment and percentage of each status:
Total loans in repayment	55,684			62,952
Loans allowance for losses	(67)	(76)	$ (67)	$ (82)	$ (59)	$ (60)
Loans, net	67,956	72,253
Credit Concentration Risk [Member] \| Accounts Receivable [Member] \| Private Education Loans - TDRs [Member]
Loans in repayment and percentage of each status:
Loans current	7,816	7,890
Total loans in repayment	8,760	9,025
Total loans, gross	9,636	9,969
Loans unamortized premium (discount)	(209)	(212)
Total loans	9,427	9,757
Loans receivable for partially charged-off loans	364	367
Loans allowance for losses	(1,040)	(1,100)
Loans, net	$ 8,751	$ 9,024
Dimensions of concentration risk	100.00%	100.00%
Credit Concentration Risk [Member] \| Accounts Receivable [Member] \| Private Education Loans - Non-TDRs [Member]
Loans in repayment and percentage of each status:
Loans current	$ 12,553	$ 12,851
Total loans in repayment	12,679	13,012
Total loans, gross	13,130	13,562
Loans unamortized premium (discount)	(482)	(547)
Total loans	12,648	13,015
Loans receivable for partially charged-off loans	276	307
Loans allowance for losses	(111)	(101)
Loans, net	$ 12,813	$ 13,221
Dimensions of concentration risk	100.00%	100.00%
Credit Concentration Risk [Member] \| Accounts Receivable [Member] \| School/Grace/Deferment [Member] \| Private Education Loans - TDRs [Member]
Loans in repayment and percentage of each status:
Total loans, gross	$ 371	$ 426
Credit Concentration Risk [Member] \| Accounts Receivable [Member] \| School/Grace/Deferment [Member] \| Private Education Loans - Non-TDRs [Member]
Loans in repayment and percentage of each status:
Total loans, gross	315	392
Credit Concentration Risk [Member] \| Accounts Receivable [Member] \| Forbearance [Member] \| Private Education Loans - TDRs [Member]
Loans in repayment and percentage of each status:
Total loans, gross	505	518
Credit Concentration Risk [Member] \| Accounts Receivable [Member] \| Forbearance [Member] \| Private Education Loans - Non-TDRs [Member]
Loans in repayment and percentage of each status:
Total loans, gross	136	158
Credit Concentration Risk [Member] \| Accounts Receivable [Member] \| FFELP Loans [Member]
Loans in repayment and percentage of each status:
Loans current	49,855	53,500
Total loans in repayment	55,684	59,551
Total loans, gross	67,454	71,730
Loans unamortized premium (discount)	569	599
Total loans	68,023	72,329
Loans allowance for losses	(67)	(76)
Loans, net	$ 67,956	$ 72,253
Dimensions of concentration risk	100.00%	100.00%
Credit Concentration Risk [Member] \| Accounts Receivable [Member] \| FFELP Loans [Member] \| School/Grace/Deferment [Member]
Loans in repayment and percentage of each status:
Total loans, gross	$ 3,530	$ 3,793
Credit Concentration Risk [Member] \| Accounts Receivable [Member] \| FFELP Loans [Member] \| Forbearance [Member]
Loans in repayment and percentage of each status:
Total loans, gross	8,240	8,386
Credit Concentration Risk [Member] \| Accounts Receivable [Member] \| Financing Receivables, 31 to 60 Days Past Due [Member] \| Private Education Loans - TDRs [Member]
Loans in repayment and percentage of each status:
Loans delinquent	$ 276	$ 344
Loans delinquent, percentage	3.20%	3.80%
Credit Concentration Risk [Member] \| Accounts Receivable [Member] \| Financing Receivables, 31 to 60 Days Past Due [Member] \| Private Education Loans - Non-TDRs [Member]
Loans in repayment and percentage of each status:
Loans delinquent	$ 51	$ 71
Loans delinquent, percentage	0.40%	0.50%
Credit Concentration Risk [Member] \| Accounts Receivable [Member] \| Financing Receivables, 31 to 60 Days Past Due [Member] \| FFELP Loans [Member]
Loans in repayment and percentage of each status:
Loans delinquent	$ 1,540	$ 1,964
Loans delinquent, percentage	2.80%	3.40%
Credit Concentration Risk [Member] \| Accounts Receivable [Member] \| Financing Receivables, 61 to 90 Days Past Due [Member] \| Private Education Loans - TDRs [Member]
Loans in repayment and percentage of each status:
Loans delinquent	$ 191	$ 235
Loans delinquent, percentage	2.20%	2.60%
Credit Concentration Risk [Member] \| Accounts Receivable [Member] \| Financing Receivables, 61 to 90 Days Past Due [Member] \| Private Education Loans - Non-TDRs [Member]
Loans in repayment and percentage of each status:
Loans delinquent	$ 28	$ 32
Loans delinquent, percentage	0.20%	0.30%
Credit Concentration Risk [Member] \| Accounts Receivable [Member] \| Financing Receivables, 61 to 90 Days Past Due [Member] \| FFELP Loans [Member]
Loans in repayment and percentage of each status:
Loans delinquent	$ 870	$ 910
Loans delinquent, percentage	1.60%	1.50%
Credit Concentration Risk [Member] \| Accounts Receivable [Member] \| Financing Receivables, 90 Days Past Due [Member] \| Private Education Loans - TDRs [Member]
Loans in repayment and percentage of each status:
Loans delinquent	$ 477	$ 556
Loans delinquent, percentage	5.40%	6.20%
Credit Concentration Risk [Member] \| Accounts Receivable [Member] \| Financing Receivables, 90 Days Past Due [Member] \| Private Education Loans - Non-TDRs [Member]
Loans in repayment and percentage of each status:
Loans delinquent	$ 47	$ 58
Loans delinquent, percentage	0.40%	0.40%
Credit Concentration Risk [Member] \| Accounts Receivable [Member] \| Financing Receivables, 90 Days Past Due [Member] \| FFELP Loans [Member]
Loans in repayment and percentage of each status:
Loans delinquent	$ 3,419	$ 3,177
Loans delinquent, percentage	6.10%	5.30%
Credit Concentration Risk [Member] \| Accounts Receivable [Member] \| Financing Receivables, Current [Member] \| Private Education Loans - TDRs [Member]
Loans in repayment and percentage of each status:
Dimensions of concentration risk	89.20%	87.40%
Credit Concentration Risk [Member] \| Accounts Receivable [Member] \| Financing Receivables, Current [Member] \| Private Education Loans - Non-TDRs [Member]
Loans in repayment and percentage of each status:
Dimensions of concentration risk	99.00%	98.80%
Credit Concentration Risk [Member] \| Accounts Receivable [Member] \| Financing Receivables, Current [Member] \| FFELP Loans [Member]
Loans in repayment and percentage of each status:
Dimensions of concentration risk	89.50%	89.80%
Credit Concentration Risk [Member] \| Accounts Receivable [Member] \| Financing Receivables, Loans In Repayment [Member] \| Private Education Loans - TDRs [Member]
Loans in repayment and percentage of each status:
Dimensions of concentration risk	90.90%	90.50%
Credit Concentration Risk [Member] \| Accounts Receivable [Member] \| Financing Receivables, Loans In Repayment [Member] \| Private Education Loans - Non-TDRs [Member]
Loans in repayment and percentage of each status:
Dimensions of concentration risk	96.60%	95.90%
Credit Concentration Risk [Member] \| Accounts Receivable [Member] \| Financing Receivables, Loans In Repayment [Member] \| FFELP Loans [Member]
Loans in repayment and percentage of each status:
Dimensions of concentration risk	82.60%	83.00%
Credit Concentration Risk [Member] \| Accounts Receivable [Member] \| Financing Receivables, Delinquent Loans in Repayment [Member] \| Private Education Loans - TDRs [Member]
Loans in repayment and percentage of each status:
Dimensions of concentration risk	10.80%	12.60%
Credit Concentration Risk [Member] \| Accounts Receivable [Member] \| Financing Receivables, Delinquent Loans in Repayment [Member] \| Private Education Loans - Non-TDRs [Member]
Loans in repayment and percentage of each status:
Dimensions of concentration risk	1.00%	1.20%
Credit Concentration Risk [Member] \| Accounts Receivable [Member] \| Financing Receivables, Delinquent Loans in Repayment [Member] \| FFELP Loans [Member]
Loans in repayment and percentage of each status:
Dimensions of concentration risk	10.50%	10.20%
Credit Concentration Risk [Member] \| Accounts Receivable [Member] \| Financing Receivables, Forbearance, Loans In Repayment [Member] \| Private Education Loans - TDRs [Member]
Loans in repayment and percentage of each status:
Dimensions of concentration risk	5.40%	5.40%
Credit Concentration Risk [Member] \| Accounts Receivable [Member] \| Financing Receivables, Forbearance, Loans In Repayment [Member] \| Private Education Loans - Non-TDRs [Member]
Loans in repayment and percentage of each status:
Dimensions of concentration risk	1.10%	1.20%
Credit Concentration Risk [Member] \| Accounts Receivable [Member] \| Financing Receivables, Forbearance, Loans In Repayment [Member] \| FFELP Loans [Member]
Loans in repayment and percentage of each status:
Dimensions of concentration risk	12.90%	12.30%