SLM (SLM) 10-Q 23 Apr 18 2018 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information	3 Months Ended
	Mar. 31, 2018shares
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q1
Trading Symbol	SLM
Entity Registrant Name	SLM CORPORATION
Entity Central Index Key	1,032,033
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding (in shares)	435,196,223

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Assets
Cash and cash equivalents	$ 1,435,649	$ 1,534,339
Available-for-sale investments at fair value (cost of $236,761 and $247,607, respectively)	229,114	244,088
Loans held for investment (net of allowance for losses of $272,123 and $251,475, respectively)	20,166,604	18,567,641
Restricted cash	120,084	101,836
Other interest-earning assets	31,637	21,586
Accrued interest receivable	1,063,449	967,482
Premises and equipment, net	97,211	89,748
Tax indemnification receivable	169,242	168,011
Other assets	93,332	84,853
Total assets	23,406,322	21,779,584
Liabilities
Deposits	16,498,646	15,505,383
Short-term borrowings	0	0
Long-term borrowings	3,744,345	3,275,270
Income taxes payable, net	145,167	102,285
Upromise member accounts	233,015	243,080
Other liabilities	175,316	179,310
Total liabilities	20,796,489	19,305,328
Commitments and contingencies
Equity
Common stock, par value $0.20 per share, 1.125 billion shares authorized: 449.0 million and 443.5 million shares issued, respectively	89,805	88,693
Additional paid-in capital	1,252,609	1,222,277
Accumulated other comprehensive income (net of tax expense of $5,005 and $1,696, respectively)	15,601	2,748
Retained earnings	990,447	868,182
Total SLM Corporation stockholders’ equity before treasury stock	2,748,462	2,581,900
Less: Common stock held in treasury at cost: 13.8 million and 11.1 million shares, respectively	(138,629)	(107,644)
Total equity	2,609,833	2,474,256
Total liabilities and equity	23,406,322	21,779,584
Series B Preferred Stock
Equity
Series B: 4 million and 4 million shares issued, respectively, at stated value of $100 per share	$ 400,000	$ 400,000

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Amortized cost	$ 236,761	$ 247,607
Allowance for loan losses	272,123	251,475
Tax benefit for accumulated other comprehensive (loss) income	$ (5,005)	$ (1,696)
Preferred stock, stated value (in dollars per share)	$ 0.20	$ 0.20
Preferred stock shares authorized (in shares)	20,000,000	20,000,000
Common stock par value (in dollars per share)	$ 0.20	$ 0.20
Common stock, shares authorized (in shares)	1,125,000,000	1,125,000,000
Common stock shares issued (in shares)	449,000,000	443,500,000
Common stock held in treasury (in shares)	13,800,000	11,100,000
Series B Preferred Stock
Preferred stock, stated value (in dollars per share)	$ 100	$ 100
Preferred stock shares outstanding (in shares)	4,000,000	4,000,000

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Interest income:
Loans	$ 430,048	$ 324,757
Investments	1,947	2,143
Cash and cash equivalents	5,236	2,588
Total interest income	437,231	329,488
Interest expense:
Deposits	77,456	44,853
Interest expense on short-term borrowings	2,393	1,236
Interest expense on long-term borrowings	24,768	15,323
Total interest expense	104,617	61,412
Net interest income	332,614	268,076
Less: provisions for credit losses	53,931	25,296
Net interest income after provisions for credit losses	278,683	242,780
Non-interest income:
Gains (losses) on derivatives and hedging activities, net	3,892	(5,378)
Other income	9,642	11,346
Total non-interest income	13,534	5,968
Non-interest expenses:
Compensation and benefits	68,317	55,464
FDIC assessment fees	8,796	7,229
Other operating expenses	47,761	39,984
Total operating expenses	124,874	102,677
Acquired intangible asset amortization expense	92	117
Total non-interest expenses	124,966	102,794
Income before income tax expense	167,251	145,954
Income tax expense	40,997	51,011
Net income	126,254	94,943
Preferred stock dividends	3,397	5,575
Net income attributable to SLM Corporation common stock	$ 122,857	$ 89,368
Basic earnings per common share attributable to SLM Corporation (in dollars per share)	$ 0.28	$ 0.21
Average common shares outstanding (in shares)	433,952	429,891
Diluted earnings per common share attributable to SLM Corporation (in dollars per share)	$ 0.28	$ 0.20
Average common and common equivalent shares outstanding (in shares)	438,977	438,735

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 126,254	$ 94,943
Other comprehensive income (loss):
Unrealized losses on investments	(4,127)	(1,567)
Unrealized gains on cash flow hedges	20,290	4,779
Total unrealized gains	16,163	3,212
Income tax expense	(3,902)	(1,232)
Other comprehensive income, net of tax expense	12,261	1,980
Total comprehensive income	$ 138,515	$ 96,923

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - USD ($) $ in Thousands	Total	Series A Preferred Stock	Series B Preferred Stock	Preferred Stock	Common Stock	Treasury Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income	Retained Earnings	Retained EarningsSeries A Preferred Stock	Retained EarningsSeries B Preferred Stock
Beginning Balance (in shares) at Dec. 31, 2016				7,300,000	428,903,559	(7,728,920)
Beginning Balance, shares issued (in shares) at Dec. 31, 2016					436,632,479
Beginning Balance at Dec. 31, 2016	$ 2,347,058			$ 565,000	$ 87,327	$ (67,484)	$ 1,175,564	$ (8,671)	$ 595,322
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	94,943								94,943
Other comprehensive income (loss), net of tax	1,980							1,980
Total comprehensive income	96,923
Cash dividends:
Cash dividends		$ (2,875)	$ (2,700)							$ (2,875)	$ (2,700)
Dividend equivalent units related to employee stock-based compensation plans	$ 0						96		(96)
Issuance of common shares (in shares)	3,738,717				3,738,717
Issuance of common shares	$ 6,535				$ 748		5,787
Tax benefit related to employee stock-based compensation	0						0
Stock-based compensation expense	$ 9,425						9,425
Shares repurchased related to employee stock-based compensation plans (in shares)	(1,603,487)				(1,603,487)	(1,603,487)
Shares repurchased related to employee stock-based compensation plans	$ (19,175)					$ (19,175)
Ending Balance (in shares) at Mar. 31, 2017				7,300,000	431,038,789	(9,332,407)
Ending Balance, shares issued (in shares) at Mar. 31, 2017					440,371,196
Ending Balance at Mar. 31, 2017	2,435,356			$ 565,000	$ 88,075	$ (86,659)	1,191,466	(6,691)	684,165
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of the adoption of the new stock compensation standard amendment | Accounting Standards Update 2016-09, New Stock Compensation Standard Amendment	165						594		(429)
Beginning Balance (in shares) at Dec. 31, 2017				4,000,000	432,376,250	(11,087,337)
Beginning Balance, shares issued (in shares) at Dec. 31, 2017					443,463,587
Beginning Balance at Dec. 31, 2017	2,474,256			$ 400,000	$ 88,693	$ (107,644)	1,222,277	2,748	868,182
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	126,254								126,254
Other comprehensive income (loss), net of tax	12,261							12,261
Total comprehensive income	138,515
Reclassification resulting from the adoption of ASU No. 2018-02 | Accounting Standards Update 2018-02	$ 0							592	(592)
Cash dividends:
Cash dividends			$ (3,397)								$ (3,397)
Issuance of common shares (in shares)	5,559,991				5,559,991
Issuance of common shares	$ 16,699				$ 1,112		15,587
Stock-based compensation expense	$ 14,745						14,745
Shares repurchased related to employee stock-based compensation plans (in shares)	(2,740,018)				(2,740,018)	(2,740,018)
Shares repurchased related to employee stock-based compensation plans	$ (30,985)					$ (30,985)
Ending Balance (in shares) at Mar. 31, 2018				4,000,000	435,196,223	(13,827,355)
Ending Balance, shares issued (in shares) at Mar. 31, 2018					449,023,578
Ending Balance at Mar. 31, 2018	$ 2,609,833			$ 400,000	$ 89,805	$ (138,629)	$ 1,252,609	$ 15,601	$ 990,447

CONSOLIDATED STATEMENTS OF CHA7

CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Series A Preferred Stock
Preferred stock dividend rate (in dollars per share)		$ 0.87
Series B Preferred Stock
Preferred stock dividend rate (in dollars per share)	$ 0.83	$ 0.67

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating activities
Net income	$ 126,254	$ 94,943
Adjustments to reconcile net income to net cash (used in) provided by operating activities:
Provisions for credit losses	53,931	25,296
Income tax expense	40,997	51,011
Amortization of brokered deposit placement fee	2,789	2,130
Amortization of ABCP Facility upfront fee	301	352
Amortization of deferred loan origination costs and loan premium/(discounts), net	2,607	1,777
Net amortization of discount on investments	475	452
Income on tax indemnification receivable	(1,231)	(1,501)
Depreciation of premises and equipment	3,117	2,585
Amortization of acquired intangibles	92	117
Stock-based compensation expense	14,745	9,425
Unrealized (gains) losses on derivatives and hedging activities, net	(3,879)	5,364
Other adjustments to net income, net	1,763	1,258
Changes in operating assets and liabilities:
Increase in accrued interest receivable	(201,776)	(153,055)
Increase in other interest-earning assets	(10,051)	(1,228)
Increase in other assets	(35,716)	(13,435)
Decrease in income taxes payable, net	(1,159)	(1,689)
Increase in accrued interest payable	11,034	6,146
Increase in payable due to entity that is a subsidiary of Navient	422	227
Decrease in other liabilities	(18,873)	(39,424)
Total adjustments	(140,412)	(104,192)
Total net cash used in operating activities	(14,158)	(9,249)
Investing activities
Loans acquired and originated	(2,300,135)	(1,892,697)
Net proceeds from sales of loans held for investment	820	1,972
Proceeds from claim payments	12,084	11,932
Net decrease in loans held for investment	735,894	506,637
Purchases of available-for-sale securities	0	(18,481)
Proceeds from sales and maturities of available-for-sale securities	10,371	8,170
Total net cash used in investing activities	(1,540,966)	(1,382,467)
Financing activities
Brokered deposit placement fee	(7,055)	(2,084)
Net increase (decrease) in certificates of deposit	694,982	(151,003)
Net increase in other deposits	323,614	83,018
Borrowings collateralized by loans in securitization trusts - issued	667,848	767,994
Borrowings collateralized by loans in securitization trusts - repaid	(200,247)	(99,884)
Issuance costs for unsecured debt offering	0	(23)
Borrowings under ABCP Facility	300,000	0
Repayment of borrowings under ABCP Facility	(300,000)	0
Fees paid on ABCP Facility	(1,063)	(1,515)
Preferred stock dividends paid	(3,397)	(5,575)
Net cash provided by financing activities	1,474,682	590,928
Net decrease in cash, cash equivalents and restricted cash	(80,442)	(800,788)
Cash, cash equivalents and restricted cash at beginning of period	1,636,175	1,972,510
Cash, cash equivalents and restricted cash at beginning of period	1,555,733	1,171,722
Cash disbursements made for:
Interest	94,737	54,648
Income taxes paid	1,894	1,426
Income taxes refunded	(990)	(32)
Reconciliation of the Consolidated Statements of Cash Flows to the Consolidated Balance Sheets
Total cash, cash equivalents and restricted cash	$ 1,636,175	$ 1,972,510

Significant Accounting Policies

Significant Accounting Policies	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Significant Accounting Policies	Significant Accounting Policies Basis of Presentation The accompanying unaudited, consolidated financial statements of SLM Corporation (“Sallie Mae,” “SLM,” the “Company,” “we,” or “us”) have been prepared in accordance with generally accepted accounting principles in the United States of America (“GAAP”) for interim financial information. Accordingly, they do not include all the information and footnotes required by GAAP for complete consolidated financial statements. The consolidated financial statements include the accounts of SLM Corporation and its majority-owned and controlled subsidiaries after eliminating the effects of intercompany accounts and transactions. In the opinion of management, all adjustments considered necessary for a fair statement of the results for the interim periods have been included. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results could differ from those estimates. Operating results for the three months ended March 31, 2018 are not necessarily indicative of the results for the year ending December 31, 2018 or for any other period. These unaudited financial statements should be read in conjunction with the audited financial statements and related notes included in our Annual Report on Form 10-K for the year ended December 31, 2017 (the “2017 Form 10-K”). Consolidation The consolidated financial statements include the accounts of the Company and its majority-owned and controlled subsidiaries after eliminating the effects of intercompany accounts and transactions. We consolidate any variable interest entity (“VIE”) where we have determined we are the primary beneficiary. The primary beneficiary is the entity which has both: (1) the power to direct the activities of the VIE that most significantly impact the VIE’s economic performance and (2) the obligation to absorb losses or receive benefits of the entity that could potentially be significant to the VIE. Recently Issued and Adopted Accounting Pronouncements In November 2016, the Financial Accounting Standards Board (the “FASB”) issued Accounting Standards Update (“ASU”) No. 2016-18, “Statement of Cash Flows (Topic 230): Restricted Cash.” Whereas restricted cash balances have traditionally been excluded from the statement of cash flows, this ASU requires restricted cash and restricted cash equivalents to be included within the beginning and ending totals of cash, cash equivalents and restricted cash presented on the statement of cash flows for all periods presented. Restricted cash and restricted cash equivalent inflows and outflows with external parties are required to be classified within the operating, investing, and/or financing activity sections of the statement of cash flows, whereas transfers between cash and cash equivalents and restricted cash and restricted cash equivalents should no longer be presented on the statement of cash flows. ASU No. 2016-18 also requires (a) the nature of the restrictions to be disclosed to help provide information about the sources and uses of these balances during a reporting period and (b) a reconciliation of the cash, cash equivalents and restricted cash totals on the statement of cash flows to the related balance sheet line items when cash, cash equivalents, and restricted cash are presented in more than one line item on the balance sheet. The reconciliation can be presented either on the face of the statement of cash flows or in the notes to the financial statements and must be provided for each period that a balance sheet is presented. We adopted the new accounting pronouncement on January 1, 2018, and the adoption did not have a material impact to our statement of cash flows. In February 2018, the FASB issued ASU No. 2018-02, “Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income,” which allows a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the tax law and tax rate changes under the Tax Cuts and Jobs Act of 2017 (the “Tax Act”) enacted on December 22, 2017. Under the Tax Act, deferred taxes were adjusted to reflect the reduction of the historical corporate income tax rate to the newly enacted corporate income tax rate, which left the tax effects on items within accumulated other comprehensive income stranded at an inappropriate tax rate. This guidance is effective for fiscal years beginning after December 15, 2018, and for interim periods within those fiscal years, with early adoption permitted. We adopted this standard effective January 1, 2018 and recorded a $ 0.6 million reclass from accumulated other comprehensive income to retained earnings in the first quarter of 2018.

Loans Held for Investment

Loans Held for Investment	3 Months Ended
	Mar. 31, 2018
Receivables [Abstract]
Loans Held for Investment	Loans Held for Investment Loans held for investment consist of Private Education Loans, FFELP Loans and Personal Loans. We use “Private Education Loans” to mean education loans to students or their families that are not made, insured or guaranteed by any state or federal government. Private Education Loans do not include loans insured or guaranteed under the previously existing Federal Family Education Loan Program (“FFELP”). We use “Personal Loans” to mean those unsecured loans to individuals that may be used for non-educational purposes. We began to opportunistically acquire Personal Loans in the fourth quarter of 2016. Our Private Education Loans are made largely to bridge the gap between the cost of higher education and the amount funded through financial aid, government loans and customers’ resources. Private Education Loans bear the full credit risk of the customer. We manage this risk through risk-performance underwriting strategies and qualified cosigners. Private Education Loans may be fixed rate or may carry a variable interest rate indexed to LIBOR. As of March 31, 2018 and December 31, 2017, 74 percent and 77 percent , respectively, of all of our Private Education Loans were indexed to LIBOR. We provide incentives for customers to include a cosigner on the loan, and the vast majority of loans in our portfolio are cosigned. We also encourage customers to make payments while in school. FFELP Loans are insured as to their principal and accrued interest in the event of default, subject to a risk-sharing level based on the date of loan disbursement. These insurance obligations are supported by contractual rights against the United States. For loans disbursed on or after July 1, 2006, we receive 97 percent reimbursement on all qualifying claims. For loans disbursed after October 1, 1993, and before July 1, 2006, we receive 98 percent reimbursement on all qualifying claims. For loans disbursed prior to October 1, 1993, we receive 100 percent reimbursement on all qualifying claims. Loans held for investment are summarized as follows: March 31, December 31, 2018 2017 Private Education Loans $ 18,794,012 $ 17,432,167 Deferred origination costs and unamortized premium/(discount) 58,814 56,378 Allowance for loan losses (252,103 ) (243,715 ) Total Private Education Loans, net 18,600,723 17,244,830 FFELP Loans 907,842 927,660 Deferred origination costs and unamortized premium/(discount) 2,566 2,631 Allowance for loan losses (1,113 ) (1,132 ) Total FFELP Loans, net 909,295 929,159 Personal Loans 675,656 400,280 Deferred origination costs and unamortized premium/(discount) (163 ) — Allowance for loan losses (18,907 ) (6,628 ) Total Personal Loans, net 656,586 393,652 Loans held for investment, net $ 20,166,604 $ 18,567,641 The estimated weighted average life of education loans in our portfolio was approximately 5.4 years and 5.5 years at March 31, 2018 and December 31, 2017 , respectively. The average balance and the respective weighted average interest rates of loans in our portfolio are summarized as follows: Three Months Ended March 31, 2018 2017 Average Balance Weighted Average Interest Rate Average Balance Weighted Average Interest Rate Private Education Loans $ 18,659,717 8.84 % $ 15,449,555 8.26 % FFELP Loans 919,717 4.25 1,003,128 3.69 Personal Loans 528,644 10.64 35,830 9.16 Total portfolio $ 20,108,078 $ 16,488,513

Allowance for Loan Losses

Allowance for Loan Losses	3 Months Ended
	Mar. 31, 2018
Receivables [Abstract]
Allowance for Loan Losses	Allowance for Loan Losses Our provision for credit losses represents the periodic expense of maintaining an allowance sufficient to absorb incurred probable losses in the held-for-investment loan portfolios. The evaluation of the allowance for loan losses is inherently subjective, as it requires material estimates that may be susceptible to significant changes. We believe the allowance for loan losses is appropriate to cover probable losses incurred in the loan portfolios. Allowance for Loan Losses Metrics Allowance for Loan Losses Three Months Ended March 31, 2018 FFELP Loans Private Education Loans Personal Loans Total Allowance for Loan Losses Beginning balance $ 1,132 $ 243,715 $ 6,628 $ 251,475 Total provision 231 41,870 13,448 55,549 Net charge-offs: Charge-offs (250 ) (37,353 ) (1,200 ) (38,803 ) Recoveries — 5,087 31 5,118 Net charge-offs (250 ) (32,266 ) (1,169 ) (33,685 ) Loan sales (1) — (1,216 ) — (1,216 ) Ending Balance $ 1,113 $ 252,103 $ 18,907 $ 272,123 Allowance: Ending balance: individually evaluated for impairment $ — $ 101,824 $ — $ 101,824 Ending balance: collectively evaluated for impairment $ 1,113 $ 150,279 $ 18,907 $ 170,299 Loans: Ending balance: individually evaluated for impairment $ — $ 1,043,103 $ — $ 1,043,103 Ending balance: collectively evaluated for impairment $ 907,842 $ 17,750,909 $ 675,656 $ 19,334,407 Net charge-offs as a percentage of average loans in repayment (annualized) (2) 0.14 % 1.01 % 0.88 % Allowance as a percentage of the ending total loan balance 0.12 % 1.34 % 2.80 % Allowance as a percentage of the ending loans in repayment (2) 0.16 % 1.95 % 2.80 % Allowance coverage of net charge-offs (annualized) 1.11 1.95 4.04 Ending total loans, gross $ 907,842 $ 18,794,012 $ 675,656 Average loans in repayment (2) $ 718,311 $ 12,747,929 $ 531,889 Ending loans in repayment (2) $ 702,965 $ 12,958,742 $ 675,656 ____________ (1) Represents fair value adjustments on loans sold. (2) Loans in repayment include loans on which borrowers are making interest only or fixed payments, as well as loans that have entered full principal and interest repayment status after any applicable grace period. Allowance for Loan Losses Three Months Ended March 31, 2017 FFELP Loans Private Education Loans Personal Loans Total Allowance for Loan Losses Beginning balance $ 2,171 $ 182,472 $ 58 $ 184,701 Total provision (316 ) 26,820 288 26,792 Net charge-offs: Charge-offs (218 ) (26,227 ) — (26,445 ) Recoveries — 3,259 — 3,259 Net charge-offs (218 ) (22,968 ) — (23,186 ) Loan sales (1) — (1,221 ) — (1,221 ) Ending Balance $ 1,637 $ 185,103 $ 346 $ 187,086 Allowance: Ending balance: individually evaluated for impairment $ — $ 87,150 $ — $ 87,150 Ending balance: collectively evaluated for impairment $ 1,637 $ 97,953 $ 346 $ 99,936 Loans: Ending balance: individually evaluated for impairment $ — $ 701,860 $ — $ 701,860 Ending balance: collectively evaluated for impairment $ 989,393 $ 14,952,994 $ 55,502 $ 15,997,889 Net charge-offs as a percentage of average loans in repayment (annualized) (2) 0.11 % 0.89 % — % Allowance as a percentage of the ending total loan balance 0.17 % 1.18 % 0.62 % Allowance as a percentage of the ending loans in repayment (2) 0.22 % 1.76 % 0.62 % Allowance coverage of net charge-offs (annualized) 1.88 2.01 — Ending total loans, gross $ 989,393 $ 15,654,854 $ 55,502 Average loans in repayment (2) $ 771,435 $ 10,265,530 $ 35,830 Ending loans in repayment (2) $ 757,052 $ 10,526,782 $ 55,502 ____________ (1) Represents fair value adjustments on loans sold. (2) Loans in repayment include loans on which borrowers are making interest only or fixed payments, as well as loans that have entered full principal and interest repayment status after any applicable grace period. Troubled Debt Restructurings (“TDRs”) All of our loans are collectively assessed for impairment, except for loans classified as TDRs (where we conduct individual assessments of impairment). We modify the terms of loans for certain borrowers when we believe such modifications may increase the ability and willingness of a borrower to make payments and thus increase the ultimate overall amount collected on a loan. These modifications generally take the form of a forbearance, a temporary interest rate reduction or an extended repayment plan. The majority of our loans that are considered TDRs involve a temporary forbearance of payments and do not change the contractual interest rate of the loan. Once a loan qualifies for TDR status, it remains a TDR for allowance purposes for the remainder of its life. As of March 31, 2018 and December 31, 2017 , approximately 62 percent and 66 percent , respectively, of TDRs were classified as such due to their forbearance status. For additional information, see Note 6, “Allowance for Loan Losses” in our 2017 Form 10-K. Within the Private Education Loan portfolio, loans greater than 90 days past due are considered to be nonperforming. FFELP Loans are at least 97 percent guaranteed as to their principal and accrued interest by the federal government in the event of default and, therefore, we do not deem FFELP Loans as nonperforming from a credit risk perspective at any point in their life cycle prior to claim payment, and continue to accrue interest on those loans through the date of claim. At March 31, 2018 and December 31, 2017 , all TDR loans had a related allowance recorded. The following table provides the recorded investment, unpaid principal balance and related allowance for our TDR loans. Recorded Investment Unpaid Principal Balance Allowance March 31, 2018 TDR Loans $ 1,061,046 $ 1,043,103 $ 101,824 December 31, 2017 TDR Loans $ 1,007,141 $ 990,351 $ 94,682 The following table provides the average recorded investment and interest income recognized for our TDR loans. Three Months Ended 2018 2017 Average Recorded Investment Interest Income Recognized Average Recorded Investment Interest Income Recognized TDR Loans $ 1,032,232 $ 17,847 $ 669,606 $ 12,257 The following table provides information regarding the loan status and aging of TDR loans. March 31, December 31, 2018 2017 Balance % Balance % TDR loans in in-school/grace/deferment (1) $ 58,939 $ 51,745 TDR loans in forbearance (2) 65,036 69,652 TDR loans in repayment (3) and percentage of each status: Loans current 823,813 89.7 % 774,222 89.1 % Loans delinquent 31-60 days (4) 47,127 5.1 48,377 5.6 Loans delinquent 61-90 days (4) 31,463 3.4 28,778 3.3 Loans delinquent greater than 90 days (4) 16,725 1.8 17,577 2.0 Total TDR loans in repayment 919,128 100.0 % 868,954 100.0 % Total TDR loans, gross $ 1,043,103 $ 990,351 _____ (1) Deferment includes customers who have returned to school or are engaged in other permitted educational activities and are not yet required to make payments on the loans (e.g., residency periods for medical students or a grace period for bar exam preparation). (2) Loans for customers who have requested extension of grace period generally during employment transition or who have temporarily ceased making full payments due to hardship or other factors, consistent with established loan program servicing policies and procedures. (3) Loans in repayment include loans on which borrowers are making interest only or fixed payments, as well as loans that have entered full principal and interest repayment status after any applicable grace period. (4) The period of delinquency is based on the number of days scheduled payments are contractually past due. The following table provides the amount of modified loans (which include forbearance and reductions in interest rates) that became TDRs in the periods presented. Additionally, for the periods presented, the table summarizes charge-offs occurring in the TDR portfolio, as well as TDRs for which a payment default occurred in the relevant period presented and within 12 months of the loan first being designated as a TDR. We define payment default as more than 60 days past due for this disclosure. Three Months Ended Three Months Ended Modified Loans (1) Charge-offs Payment- Default Modified Loans (1) Charge-offs Payment- Default TDR Loans $ 84,174 $ 15,460 $ 29,757 $ 112,206 $ 10,523 $ 25,526 _____ (1) Represents the principal balance of loans that have been modified during the period and resulted in a TDR. Private Education Loan Key Credit Quality Indicators FFELP Loans are at least 97 percent insured and guaranteed as to their principal and accrued interest in the event of default; therefore, there are no key credit quality indicators associated with FFELP Loans. For Private Education Loans, the key credit quality indicators are FICO scores, the existence of a cosigner, the loan status and loan seasoning. The FICO scores are assessed at original approval and periodically refreshed/updated through the loan’s term. The following table highlights the gross principal balance of our Private Education Loan portfolio stratified by key credit quality indicators. Private Education Loans Credit Quality Indicators March 31, 2018 December 31, 2017 Credit Quality Indicators: Balance (1) % of Balance Balance (1) % of Balance Cosigners: With cosigner $ 16,889,477 90 % $ 15,658,539 90 % Without cosigner 1,904,535 10 1,773,628 10 Total $ 18,794,012 100 % $ 17,432,167 100 % FICO at Original Approval (2) : Less than 670 $ 1,257,596 6 % $ 1,153,591 6 % 670-699 2,810,526 15 2,596,959 15 700-749 6,168,342 33 5,714,554 33 Greater than or equal to 750 8,557,548 46 7,967,063 46 Total $ 18,794,012 100 % $ 17,432,167 100 % Seasoning (3) : 1-12 payments $ 4,754,416 25 % $ 4,256,592 24 % 13-24 payments 3,256,637 17 3,229,465 19 25-36 payments 2,492,490 13 2,429,238 14 37-48 payments 1,583,375 9 1,502,327 9 More than 48 payments 1,337,110 7 1,256,813 7 Not yet in repayment 5,369,984 29 4,757,732 27 Total $ 18,794,012 100 % $ 17,432,167 100 % (1) Balance represents gross Private Education Loans. (2) Represents the higher credit score of the cosigner or the borrower. (3) Number of months in active repayment (whether interest only payment, fixed payment, or full principal and interest payment status) for which a scheduled payment was due. The following table provides information regarding the loan status of our Private Education Loans. Loans in repayment include loans making interest only or fixed payments, as well as loans that have entered full principal and interest repayment status after any applicable grace period. Private Education Loans March 31, December 31, 2018 2017 Balance % Balance % Loans in-school/grace/deferment (1) $ 5,369,984 $ 4,757,732 Loans in forbearance (2) 465,286 468,402 Loans in repayment and percentage of each status: Loans current 12,635,627 97.5 % 11,911,128 97.6 % Loans delinquent 31-60 days (3) 179,989 1.4 179,002 1.5 Loans delinquent 61-90 days (3) 95,974 0.7 78,292 0.6 Loans delinquent greater than 90 days (3) 47,152 0.4 37,611 0.3 Total Private Education Loans in repayment 12,958,742 100.0 % 12,206,033 100.0 % Total Private Education Loans, gross 18,794,012 17,432,167 Private Education Loans deferred origination costs and unamortized premium/(discount) 58,814 56,378 Total Private Education Loans 18,852,826 17,488,545 Private Education Loans allowance for losses (252,103 ) (243,715 ) Private Education Loans, net $ 18,600,723 $ 17,244,830 Percentage of Private Education Loans in repayment 69.0 % 70.0 % Delinquencies as a percentage of Private Education Loans in repayment 2.5 % 2.4 % Loans in forbearance as a percentage of Private Education Loans in repayment and forbearance 3.5 % 3.7 % (1) Deferment includes customers who have returned to school or are engaged in other permitted educational activities and are not yet required to make payments on the loans (e.g., residency periods for medical students or a grace period for bar exam preparation). (2) Loans for customers who have requested extension of grace period generally during employment transition or who have temporarily ceased making full payments due to hardship or other factors, consistent with established loan program servicing policies and procedures. (3) The period of delinquency is based on the number of days scheduled payments are contractually past due. Personal Loan Key Credit Quality Indicators For Personal Loans, the key credit quality indicators are FICO scores and loan seasoning. The FICO scores are assessed at original approval and periodically refreshed/updated through the loan’s term. The following table highlights the gross principal balance of our Personal Loan portfolio stratified by key credit quality indicators. Personal Loans Credit Quality Indicators March 31, 2018 December 31, 2017 Credit Quality Indicators: Balance (1) % of Balance Balance (1) % of Balance FICO at Original Approval: Less than 670 $ 52,417 8 % $ 32,156 8 % 670-699 193,246 29 114,731 29 700-749 307,539 45 182,025 45 Greater than or equal to 750 122,454 18 71,368 18 Total $ 675,656 100 % $ 400,280 100 % Seasoning (2) : 0-12 payments $ 649,996 96 % $ 400,280 100 % 13-24 payments 25,660 4 — — 25-36 payments — — — — 37-48 payments — — — — More than 48 payments — — — — Total $ 675,656 100 % $ 400,280 100 % (1) Balance represents gross Personal Loans. (2) Number of months in active repayment for which a scheduled payment was due. Accrued Interest Receivable The following table provides information regarding accrued interest receivable on our Private Education Loans. The table also discloses the amount of accrued interest on loans greater than 90 days past due as compared to our allowance for uncollectible interest. The allowance for uncollectible interest exceeds the amount of accrued interest on our 90 days past due Private Education Loan portfolio for all periods presented. Private Education Loans Accrued Interest Receivable Total Interest Receivable Greater Than 90 Days Past Due Allowance for Uncollectible Interest March 31, 2018 $ 1,045,577 $ 1,783 $ 4,694 December 31, 2017 $ 951,138 $ 1,372 $ 4,664

Deposits

Deposits	3 Months Ended
	Mar. 31, 2018
Banking and Thrift [Abstract]
Deposits	Deposits The following table summarizes total deposits at March 31, 2018 and December 31, 2017 . March 31, December 31, 2018 2017 Deposits - interest bearing $ 16,497,006 $ 15,504,330 Deposits - non-interest bearing 1,640 1,053 Total deposits $ 16,498,646 $ 15,505,383 Our total deposits of $ 16.5 billion were comprised of $ 8.6 billion in brokered deposits and $ 7.9 billion in retail and other deposits at March 31, 2018 , compared to total deposits of $15.5 billion , which were comprised of $8.2 billion in brokered deposits and $7.3 billion in retail and other deposits, at December 31, 2017. Interest bearing deposits as of March 31, 2018 and December 31, 2017 consisted of retail and brokered non-maturity savings deposits, retail and brokered non-maturity money market deposits (“MMDAs”) and retail and brokered certificates of deposit (“CDs”). Interest bearing deposits include deposits from Educational 529 and Health Savings plans that diversify our funding sources and additional deposits we consider to be core. These and other large omnibus accounts, aggregating the deposits of many individual depositors, represented $5.8 billion of our deposit total as of March 31, 2018 , compared with $ 5.5 billion at December 31, 2017. Some of our deposit products are serviced by third-party providers. Placement fees associated with the brokered CDs are amortized into interest expense using the effective interest rate method. We recognized placement fee expense of $ 2.8 million and $2.1 million in the three months ended March 31, 2018 and 2017, respectively. Fees paid to third-party brokers related to brokered CDs were $ 7.1 million and $2.1 million for the three months ended March 31, 2018 and 2017, respectively. Interest bearing deposits at March 31, 2018 and December 31, 2017 are summarized as follows: March 31, 2018 December 31, 2017 Amount Qtr.-End Weighted Average Stated Rate (1) Amount Year-End Weighted Average Stated Rate (1) Money market $ 8,107,996 2.01 % $ 7,731,966 1.80 % Savings 681,024 1.40 738,243 1.10 Certificates of deposit 7,707,986 2.13 7,034,121 1.93 Deposits - interest bearing $ 16,497,006 $ 15,504,330 ____________ (1) Includes the effect of interest rate swaps in effective hedge relationships. As of March 31, 2018 and December 31, 2017 , there were $ 404.5 million and $395.5 million, respectively, of deposits exceeding Federal Deposit Insurance Corporation (“FDIC”) insurance limits. Accrued interest on deposits was $36.8 million and $27.8 million at March 31, 2018 and December 31, 2017 , respectively.

Borrowings

Borrowings	3 Months Ended
	Mar. 31, 2018
Debt Disclosure [Abstract]
Borrowings	Borrowings Outstanding borrowings consist of unsecured debt and secured borrowings issued through our term asset-backed securitization (“ABS”) program and our asset-backed commercial paper (“ABCP”) funding facility (the “ABCP Facility”). The following table summarizes our borrowings at March 31, 2018 and December 31, 2017 . March 31, 2018 December 31, 2017 Short-Term Long-Term Total Short-Term Long-Term Total Unsecured borrowings: Unsecured debt $ — $ 196,741 $ 196,741 $ — $ 196,539 $ 196,539 Total unsecured borrowings — 196,741 196,741 — 196,539 196,539 Secured borrowings: Private Education Loan term securitizations — 3,547,604 3,547,604 — 3,078,731 3,078,731 ABCP Facility — — — — — — Total secured borrowings — 3,547,604 3,547,604 — 3,078,731 3,078,731 Total $ — $ 3,744,345 $ 3,744,345 $ — $ 3,275,270 $ 3,275,270 Short-term Borrowings Asset-Backed Commercial Paper Funding Facility On February 21, 2018, we amended and extended the maturity of our $750 million ABCP Facility. We hold 100 percent of the residual interest in the ABCP Facility trust. Under the amended ABCP Facility, we incur financing costs of between 0.35 percent and 0.45 percent on unused borrowing capacity and approximately 3-month LIBOR plus 0.85 percent on outstandings. The amended ABCP Facility extends the revolving period, during which we may borrow, repay and reborrow funds, until February 20, 2019. The scheduled amortization period, during which amounts outstanding under the ABCP Facility must be repaid, ends on February 20, 2020 (or earlier, if certain material adverse events occur). At both March 31, 2018 and December 31, 2017, there were no borrowings outstanding under the ABCP Facility. We expect to amend and extend the ABCP Facility on an annual basis. Long-term Borrowings Unsecured Debt On April 5, 2017, we issued an unsecured debt offering of $200 million of 5.125 percent Senior Notes due April 5, 2022 at par. At March 31, 2018, the outstanding balance was $197 million . Secured Financings On March 21, 2018, we executed our $670 million SMB Private Education Loan Trust 2018-A term ABS transaction, which was accounted for as a secured financing. We sold $670 million of notes to third parties and retained a 100 percent interest in the residual certificates issued in the securitization, raising approximately $668 million of gross proceeds. The Class A and Class B notes had a weighted average life of 4.43 years and priced at a weighted average LIBOR equivalent cost of 1-month LIBOR plus 0.78 percent . At March 31, 2018 , $701 million of our Private Education Loans were encumbered because of this transaction. Secured Financings at Issuance Issue Date Issued Total Issued Weighted Average Cost of Funds (1) Weighted Average Life (in years) Private Education: 2016-A May 2016 $ 501,000 1-month LIBOR plus 1.38% 4.01 2016-B July 2016 607,000 1-month LIBOR plus 1.36% 4.01 2016-C October 2016 674,000 1-month LIBOR plus 1.15% 4.27 Total notes issued in 2016 $ 1,782,000 Total loan and accrued interest amount securitized at inception in 2016 $ 2,107,042 2017-A February 2017 $ 772,000 1-month LIBOR plus 0.93% 4.27 2017-B November 2017 676,000 1-month LIBOR plus 0.80% 4.07 Total notes issued in 2017 $ 1,448,000 Total loan and accrued interest amount securitized at inception in 2017 $ 1,606,804 2018-A March 2018 $ 670,000 1-month LIBOR plus 0.78% 4.43 Total notes issued in 2018 $ 670,000 Total loan and accrued interest amount securitized at inception in 2018 $ 744,917 ____________ (1) Represents LIBOR equivalent cost of funds for floating and fixed rate bonds, excluding issuance costs. Consolidated Funding Vehicles We consolidate our financing entities that are VIEs as a result of our being the entities’ primary beneficiary. As a result, these financing VIEs are accounted for as secured borrowings. We consolidate the following financing VIEs as of March 31, 2018 and December 31, 2017 , respectively: March 31, 2018 Debt Outstanding Carrying Amount of Assets Securing Debt Outstanding Short-Term Long-Term Total Loans Restricted Cash Other Assets (1) Total Secured borrowings: Private Education Loan term securitizations $ — $ 3,547,604 $ 3,547,604 $ 4,243,820 $ 106,351 $ 280,646 $ 4,630,817 ABCP Facility — — — — 8,658 9,884 18,542 Total $ — $ 3,547,604 $ 3,547,604 $ 4,243,820 $ 115,009 $ 290,530 $ 4,649,359 December 31, 2017 Debt Outstanding Carrying Amount of Assets Securing Debt Outstanding Short-Term Long-Term Total Loans Restricted Cash Other Assets (1) Total Secured borrowings: Private Education Loan term securitizations $ — $ 3,078,731 $ 3,078,731 $ 3,691,024 $ 95,966 $ 240,208 $ 4,027,198 ABCP Facility — — — — 1,017 161 1,178 Total $ — $ 3,078,731 $ 3,078,731 $ 3,691,024 $ 96,983 $ 240,369 $ 4,028,376 ____ (1) Other assets primarily represent accrued interest receivable. Other Borrowing Sources We maintain discretionary uncommitted Federal Funds lines of credit with various correspondent banks, which totaled $125 million at March 31, 2018 . The interest rate we are charged on these lines of credit is priced at Fed Funds plus a spread at the time of borrowing, and is payable daily. We did not utilize these lines of credit in the three months ended March 31, 2018 or in the year ended December 31, 2017 . We established an account at the Federal Reserve Bank (“FRB”) to meet eligibility requirements for access to the Primary Credit borrowing facility at the FRB’s Discount Window (the “Window”). The Primary Credit borrowing facility is a lending program available to depository institutions that are in generally sound financial condition. All borrowings at the Window must be fully collateralized. We can pledge to the FRB asset-backed and mortgage-backed securities, as well as FFELP Loans and Private Education Loans, as collateral for borrowings at the Window. Generally, collateral value is assigned based on the estimated fair value of the pledged assets. At March 31, 2018 and December 31, 2017 , the value of our pledged collateral at the FRB totaled $2.5 billion and $2.6 billion, respectively. The interest rate charged to us is the discount rate set by the FRB. We did not utilize this facility in the three months ended March 31, 2018 or in the year ended December 31, 2017 .

Derivative Financial Instrument

Derivative Financial Instruments	3 Months Ended
	Mar. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	Derivative Financial Instruments We maintain an overall interest rate risk management strategy that incorporates the use of derivative instruments to reduce the economic effect of interest rate changes. Our goal is to manage interest rate sensitivity by modifying the repricing frequency and underlying index characteristics of certain balance sheet assets or liabilities so any adverse impacts related to movements in interest rates are managed within low to moderate limits. As a result of interest rate fluctuations, hedged balance sheet positions will appreciate or depreciate in market value or create variability in cash flows. Income or loss on the derivative instruments linked to the hedged item will generally offset the effect of this unrealized appreciation or depreciation or volatility in cash flows for the period the item is being hedged. We view this strategy as a prudent management of interest rate risk. Please refer to Note 11, “Derivative Financial Instruments” in our 2017 Form 10-K for a full discussion of our risk management strategy. Title VII of the Dodd-Frank Wall Street Reform and Consumer Protection Act of 2010 (the “Dodd-Frank Act”) requires all standardized derivatives, including most interest rate swaps, to be submitted for clearing to central counterparties to reduce counterparty risk. Two of the central counterparties we use are the Chicago Mercantile Exchange (“CME”) and the London Clearing House (“LCH”). The CME and the LCH made amendments to their respective rules that resulted in the prospective accounting treatment of certain daily variation margin payments being considered as the legal settlement of the outstanding exposure of the derivative instead of the posting of collateral. The CME rule changes, which became effective in January 2017, and the LCH rule changes, which became effective in January 2018, result in all variation margin payments on derivatives cleared through the CME and LCH being accounted for as legal settlement. As of March 31, 2018 , $5.7 billion notional of our derivative contracts were cleared on the CME and $0.7 billion were cleared on the LCH. The derivative contracts cleared through the CME and LCH represent 89.8 percent and 10.2 percent , respectively, of our total notional derivative contracts of $6.4 billion at March 31, 2018 . For derivatives cleared through the CME and LCH, the net gain (loss) position includes the variation margin amounts as settlement of the derivative and not collateral against the fair value of the derivative. Interest income (expense) related to variation margin on derivatives that are not designated as hedging instruments or are designated as fair value relationships is recognized as a gain (loss) rather than as interest income (expense). Changes in fair value for derivatives not designated as hedging instruments will be presented as realized gains (losses). Our exposure is limited to the value of the derivative contracts in a gain position less any collateral held and plus any collateral posted. When there is a net negative exposure, we consider our exposure to the counterparty to be zero. At March 31, 2018 and December 31, 2017, we had a net positive exposure (derivative gain positions to us, less collateral held by us and plus collateral posted with counterparties) related to derivatives of $31.3 million and $19.6 million, respectively. Summary of Derivative Financial Statement Impact The following tables summarize the fair values and notional amounts of all derivative instruments at March 31, 2018 and December 31, 2017 , and their impact on earnings and other comprehensive income for the three months ended March 31, 2018 and 2017. Please refer to Note 11, “Derivative Financial Instruments” in our 2017 Form 10-K for a full discussion of cash flow hedges, fair value hedges, and trading activities. Impact of Derivatives on the Consolidated Balance Sheet Cash Flow Hedges Fair Value Hedges Trading Total March 31, December 31, March 31, December March 31, December March 31, December 2018 2017 2018 2017 2018 2017 2018 2017 Fair Values (1) Hedged Risk Exposure Derivative Assets: (2) Interest rate swaps Interest rate $ — $ — $ 794 $ 630 $ — $ 182 $ 794 $ 812 Derivative Liabilities: (2) Interest rate swaps Interest rate (1,053 ) (2,584 ) — — (36 ) — (1,089 ) (2,584 ) Total net derivatives $ (1,053 ) $ (2,584 ) $ 794 $ 630 $ (36 ) $ 182 $ (295 ) $ (1,772 ) ___________ (1) Fair values reported include variation margin as legal settlement of the derivative contract and accrued interest. Assets and liabilities are presented without consideration of master netting agreements. Derivatives are carried on the balance sheet based on net position by counterparty under master netting agreements, and classified in other assets or other liabilities depending on whether in a net positive or negative position. (2) The following table reconciles gross positions with the impact of master netting agreements to the balance sheet classification: Other Assets Other Liabilities March 31, December 31, March 31, December 31, 2018 2017 2018 2017 Gross position (1) $ 794 $ 812 $ (1,089 ) $ (2,584 ) Impact of master netting agreement (794 ) (812 ) 794 812 Derivative values with impact of master netting agreements (as carried on balance sheet) — — (295 ) (1,772 ) Cash collateral pledged (2) — — 31,637 21,586 Net position $ — $ — $ 31,342 $ 19,814 __________ (1) Gross position amounts include accrued interest and variation margin as legal settlement of the derivative contract. (2) Cash collateral pledged excludes amounts that represent legal settlement of the derivative contracts. Cash Flow Fair Value Derivatives Not Designated as Hedges Total March 31, December 31, March 31, December 31, March 31, December 31, March 31, December 31, 2018 2017 2018 2017 2018 2017 2018 2017 Notional Values Interest rate swaps $ 1,376,816 $ 1,408,649 $ 3,867,204 $ 3,062,849 $ 1,161,000 $ 987,577 $ 6,405,020 $ 5,459,075 Other (1) $ — $ — $ — $ — $ 5,476 $ 3,245 $ 5,476 $ 3,245 ________ (1) “Other” includes embedded derivatives included in forward purchase contracts. Impact of Derivatives on the Consolidated Statements of Income Three Months Ended 2018 2017 Fair Value Hedges Interest rate swaps: Hedge ineffectiveness realized gains (losses) recorded in earnings (1) $ 5,853 $ (4,167 ) Realized gains (losses) recorded in interest expense (514 ) 4,547 Total $ 5,339 $ 380 Cash Flow Hedges Interest rate swaps: Hedge ineffectiveness gains (losses) recorded in earnings (1) $ 2,684 $ (72 ) Realized losses recorded in interest expense (1,562 ) (3,339 ) Total $ 1,122 $ (3,411 ) Trading Interest rate swaps: Interest reclassification $ 110 $ 80 Realized losses recorded in earnings (4,755 ) (1,219 ) Total (1) (4,645 ) (1,139 ) Total $ 1,816 $ (4,170 ) ________ (1) Amounts included in “gains (losses) on derivatives and hedging activities, net” in the consolidated statements of income. Impact of Derivatives on the Statements of Changes in Stockholders’ Equity Three Months Ended March 31, 2018 2017 Amount of gain recognized in other comprehensive income (loss) $ 18,728 $ 1,440 Less: amount of loss reclassified in interest expense (1) (1,562 ) (3,339 ) Total change in other comprehensive income (loss) for unrealized gains on derivatives, before income tax (expense) benefit $ 20,290 $ 4,779 ___________ (1) Amounts included in “realized losses recorded in interest expense” in the “Impact of Derivatives on the Consolidated Statements of Income” table. Cash Collateral As of March 31, 2018 , cash collateral held and pledged excludes amounts that represent legal settlement of the derivative contracts held with CME and LCH. Cash collateral held related to derivative exposure between us and our derivatives counterparties was zero at both March 31, 2018 and December 31, 2017 . Collateral held is recorded in “Other Liabilities” on the consolidated balance sheets. Cash collateral pledged related to derivative exposure between us and our derivatives counterparties was $31.6 million and $21.6 million at March 31, 2018 and December 31, 2017 , respectively. Collateral pledged is recorded in “Other interest-earning assets” on the consolidated balance sheets.

Stockholders' Equity

Stockholders' Equity	3 Months Ended
	Mar. 31, 2018
Equity [Abstract]
Stockholders' Equity	Stockholders’ Equity Common Stock The following table summarizes our common share repurchases and issuances. Three Months Ended (Shares and per share amounts in actuals) 2018 2017 Shares repurchased related to employee stock-based compensation plans (1)(2) 2,740,018 1,603,487 Average purchase price per share $ 11.31 $ 11.96 Common shares issued (3) 5,559,991 3,738,717 __________________ (1) Comprised of shares withheld from stock option exercises and vesting of restricted stock for employees’ tax withholding obligations and shares tendered by employees to satisfy option exercise costs. (2) At the present time, we do not intend to initiate a publicly announced share repurchase program. (3) Common shares issued under our various compensation and benefit plans. The closing price of our common stock on March 29, 2018 was $11.21 .

Earnings per Common Share

Earnings per Common Share	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Earnings per Common Share	Earnings per Common Share Basic earnings per common share (“EPS”) are calculated using the weighted average number of shares of common stock outstanding during each period. A reconciliation of the numerators and denominators of the basic and diluted EPS calculations follows. Three Months Ended March 31, (In thousands, except per share data) 2018 2017 Numerator: Net income $ 126,254 $ 94,943 Preferred stock dividends 3,397 5,575 Net income attributable to SLM Corporation common stock $ 122,857 $ 89,368 Denominator: Weighted average shares used to compute basic EPS 433,952 429,891 Effect of dilutive securities: Dilutive effect of stock options, restricted stock, restricted stock units and Employee Stock Purchase Plan (“ESPP”) (1)(2) 5,025 8,844 Weighted average shares used to compute diluted EPS 438,977 438,735 Basic earnings per common share attributable to SLM Corporation $ 0.28 $ 0.21 Diluted earnings per common share attributable to SLM Corporation $ 0.28 $ 0.20 ________________ (1) Includes the potential dilutive effect of additional common shares that are issuable upon exercise of outstanding stock options, restricted stock, restricted stock units, and the outstanding commitment to issue shares under the ESPP, determined by the treasury stock method. (2) For the three months ended March 31, 2018 and 2017, securities covering approximately 0 and 0 shares, respectively, were outstanding but not included in the computation of diluted earnings per share because they were anti-dilutive.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements We use estimates of fair value in applying various accounting standards for our financial statements. We categorize our fair value estimates based on a hierarchical framework associated with three levels of price transparency utilized in measuring financial instruments at fair value. For additional information regarding our policies for determining fair value and the hierarchical framework, see Note 2, “Significant Accounting Policies - Fair Value Measurement” in our 2017 Form 10-K. During the three months ended March 31, 2018 , there were no significant transfers of financial instruments between levels or changes in our methodology or assumptions used to value our financial instruments. The following table summarizes the valuation of our financial instruments that are marked to fair value on a recurring basis. Fair Value Measurements on a Recurring Basis March 31, 2018 December 31, 2017 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets Available-for-sale investments $ — $ 229,114 $ — $ 229,114 $ — $ 244,088 $ — $ 244,088 Derivative instruments — 794 — 794 — 812 — 812 Total $ — $ 229,908 $ — $ 229,908 $ — $ 244,900 $ — $ 244,900 Liabilities Derivative instruments $ — $ (1,089 ) $ — $ (1,089 ) $ — $ (2,584 ) $ — $ (2,584 ) Total $ — $ (1,089 ) $ — $ (1,089 ) $ — $ (2,584 ) $ — $ (2,584 ) The following table summarizes the fair values of our financial assets and liabilities, including derivative financial instruments. March 31, 2018 December 31, 2017 Fair Value Carrying Value Difference Fair Value Carrying Value Difference Earning assets Loans held for investment, net $ 22,264,191 $ 20,166,604 $ 2,097,587 $ 20,673,136 $ 18,567,641 $ 2,105,495 Cash and cash equivalents 1,435,649 1,435,649 — 1,534,339 1,534,339 — Available-for-sale investments 229,114 229,114 — 244,088 244,088 — Accrued interest receivable 1,063,449 1,063,449 — 967,482 967,482 — Tax indemnification receivable 169,242 169,242 — 168,011 168,011 — Derivative instruments 794 794 — 812 812 — Total earning assets $ 25,162,439 $ 23,064,852 $ 2,097,587 $ 23,587,868 $ 21,482,373 $ 2,105,495 Interest-bearing liabilities Money-market and savings accounts $ 8,789,020 $ 8,789,020 $ — $ 8,470,209 $ 8,470,209 $ — Certificates of deposit 8,095,950 7,707,986 (387,964 ) 7,044,208 7,034,121 (10,087 ) Long-term borrowings 3,731,696 3,744,345 12,649 3,299,871 3,275,270 (24,601 ) Accrued interest payable 46,396 46,396 — 35,363 35,363 — Derivative instruments 1,089 1,089 — 2,584 2,584 — Total interest-bearing liabilities $ 20,664,151 $ 20,288,836 $ (375,315 ) $ 18,852,235 $ 18,817,547 $ (34,688 ) Excess of net asset fair value over carrying value $ 1,722,272 $ 2,070,807 Please refer to Note 15, “Fair Value Measurements” in our 2017 Form 10-K for a full discussion of the methods and assumptions used to estimate the fair value of each class of financial instruments.

Arrangements with Navient Corpo

Arrangements with Navient Corporation	3 Months Ended
	Mar. 31, 2018
Related Party Transactions [Abstract]
Arrangements with Navient Corporation	Arrangements with Navient Corporation In connection with the separation of Navient Corporation (“Navient”) from SLM (“the Spin-Off”), we entered into a separation and distribution agreement (the “Separation and Distribution Agreement”) and other ancillary agreements with Navient. Please refer to Note 16, “Arrangements with Navient Corporation” in our 2017 Form 10-K for a full discussion of these agreements. Indemnification Obligations Navient is responsible for, and has agreed to indemnify us against, all claims, actions, damages, losses or expenses that may arise from the conduct of all activities of pre-Spin-Off SLM Corporation (“pre-Spin-Off SLM”) occurring prior to the Spin-Off other than those specifically excluded in the Separation and Distribution Agreement. Some significant examples of the types of indemnification obligations Navient has under the Separation and Distribution Agreement and related ancillary agreements include: • Navient will indemnify the Company and Sallie Mae Bank, a Utah industrial bank subsidiary of the Company (the “Bank”), for any liabilities, costs or expenses they may incur arising from any action or threatened action related to the servicing, operations and collections activities of pre-Spin-Off SLM and its subsidiaries with respect to Private Education Loans and FFELP Loans that were assets of the Bank or Navient at the time of the Spin-Off; provided that written notice was provided to Navient on or prior to April 30, 2017, the third anniversary date of the Spin-Off. Navient will not indemnify for changes in law or changes in prior existing interpretations of law that occur on or after April 30, 2014. • Pursuant to a tax sharing agreement, Navient has agreed to indemnify us for $283 million in deferred taxes that we are legally responsible for but that relate to gains recognized by our predecessor on debt repurchases made prior to the Spin-Off. The remaining amount of this indemnification at March 31, 2018 was $35 million . In connection with the Spin-Off, we also recorded a liability related to uncertain tax positions of $27 million for which we are indemnified by Navient. As of March 31, 2018 , the remaining balance of the indemnification receivable related to those uncertain tax positions was $25 million . In addition, we believe we are indemnified by Navient for uncertain tax positions relating to historical transactions among entities that are now subsidiaries of Navient that should have been recorded at the time of the Spin-Off. The remaining balance of the indemnification receivable related to those uncertain tax positions was $109 million at March 31, 2018 .

Regulatory Capital

Regulatory Capital	3 Months Ended
	Mar. 31, 2018
Banking and Thrift [Abstract]
Regulatory Capital	Regulatory Capital The Bank is subject to various regulatory capital requirements administered by the FDIC and the Utah Department of Financial Institutions (the “UDFI”). Failure to meet minimum capital requirements can initiate certain mandatory and possibly additional discretionary actions by regulators that, if undertaken, could have a direct material adverse effect on our business, results of operation and financial condition. Under the FDIC’s regulations implementing the Basel III capital framework (“U.S. Basel III”) and the regulatory framework for prompt corrective action, the Bank must meet specific capital standards that involve quantitative measures of its assets, liabilities and certain off-balance sheet items as calculated under regulatory accounting practices. The Bank’s capital amounts and its classification under the prompt corrective action framework are also subject to qualitative judgments by the regulators about components of capital, risk weightings and other factors. The Bank is required to report regulatory capital and ratios in accordance with U.S. Basel III. Among other things, U.S. Basel III established Common Equity Tier 1 as a tier of capital, modified methods for calculating risk-weighted assets, introduced a capital conservation buffer (which is being phased in over several years), and revised the capital thresholds of the prompt corrective action framework, including the “well capitalized” standard. “Well capitalized” regulatory requirements are the quantitative measures established by regulation to ensure capital adequacy. To qualify as “well capitalized,” the Bank must maintain minimum amounts and ratios (set forth in the table below) of Common Equity Tier 1, Tier 1 and Total capital to risk-weighted assets and of Tier 1 capital to average assets. The following capital amounts and ratios are based upon the Bank’s assets. Actual “Well Capitalized” Amount Ratio Amount Ratio As of March 31, 2018: Common Equity Tier 1 Capital (to Risk-Weighted Assets) $ 2,494,964 11.7 % $ 1,385,322 > 6.5 % Tier 1 Capital (to Risk-Weighted Assets) $ 2,494,964 11.7 % $ 1,705,011 > 8.0 % Total Capital (to Risk-Weighted Assets) $ 2,761,446 13.0 % $ 2,131,264 > 10.0 % Tier 1 Capital (to Average Assets) $ 2,494,964 11.0 % $ 1,138,524 > 5.0 % As of December 31, 2017: Common Equity Tier 1 Capital (to Risk-Weighted Assets) $ 2,350,081 11.9 % $ 1,288,435 > 6.5 % Tier 1 Capital (to Risk-Weighted Assets) $ 2,350,081 11.9 % $ 1,585,767 > 8.0 % Total Capital (to Risk-Weighted Assets) $ 2,597,926 13.1 % $ 1,982,208 > 10.0 % Tier 1 Capital (to Average Assets) $ 2,350,081 11.0 % $ 1,067,739 > 5.0 % Bank Dividends The Bank is chartered under the laws of the State of Utah and its deposits are insured by the FDIC. The Bank’s ability to pay dividends is subject to the laws of Utah and the regulations of the FDIC. Generally, under Utah’s industrial bank laws and regulations as well as FDIC regulations, the Bank may pay dividends from its net profits without regulatory approval if, following the payment of the dividend, the Bank’s capital and surplus would not be impaired. The Bank paid no dividends for the three months ended March 31, 2018 and March 31, 2017 .

Commitments, Contingencies and

Commitments, Contingencies and Guarantees	3 Months Ended
	Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments, Contingencies and Guarantees	Commitments, Contingencies and Guarantees Commitments When we approve a Private Education Loan at the beginning of an academic year, that approval may cover the borrowing for the entire academic year. As such, we do not always disburse the full amount of the loan at the time of such approval, but instead have a commitment to fund a portion of the loan at a later date (usually at the start of the second semester or subsequent trimesters). At March 31, 2018 , we had $ 0.5 billion of outstanding contractual loan commitments which we expect to fund during the remainder of the 2017/2018 academic year. At March 31, 2018 , we had a $ 0.3 million reserve recorded in “Other Liabilities” to cover expected losses that may occur during the one -year loss emergence period on these unfunded commitments. Contingencies In the ordinary course of business, we and our subsidiaries are routinely defendants in or parties to pending and threatened legal actions and proceedings, including actions brought on behalf of various classes of claimants. These actions and proceedings may be based on alleged violations of consumer protection, securities, employment and other laws. In certain of these actions and proceedings, claims for substantial monetary damage may be asserted against us and our subsidiaries. It is common for the Company, our subsidiaries and affiliates to receive information and document requests and investigative demands from state attorneys general, legislative committees, and administrative agencies. These requests may be for informational or regulatory purposes and may relate to our business practices, the industries in which we operate, or other companies with whom we conduct business. Our practice has been and continues to be to cooperate with these bodies and be responsive to any such requests. We are required to establish reserves for litigation and regulatory matters where those matters present loss contingencies that are both probable and estimable. When loss contingencies are not both probable and estimable, we do not establish reserves. Based on current knowledge, management does not believe there are loss contingencies, if any, arising from pending investigations, litigation or regulatory matters for which reserves should be established.

Significant Accounting Polici21

Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited, consolidated financial statements of SLM Corporation (“Sallie Mae,” “SLM,” the “Company,” “we,” or “us”) have been prepared in accordance with generally accepted accounting principles in the United States of America (“GAAP”) for interim financial information. Accordingly, they do not include all the information and footnotes required by GAAP for complete consolidated financial statements. The consolidated financial statements include the accounts of SLM Corporation and its majority-owned and controlled subsidiaries after eliminating the effects of intercompany accounts and transactions. In the opinion of management, all adjustments considered necessary for a fair statement of the results for the interim periods have been included. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results could differ from those estimates. Operating results for the three months ended March 31, 2018 are not necessarily indicative of the results for the year ending December 31, 2018 or for any other period. These unaudited financial statements should be read in conjunction with the audited financial statements and related notes included in our Annual Report on Form 10-K for the year ended December 31, 2017 (the “2017 Form 10-K”).
Consolidation	Consolidation The consolidated financial statements include the accounts of the Company and its majority-owned and controlled subsidiaries after eliminating the effects of intercompany accounts and transactions. We consolidate any variable interest entity (“VIE”) where we have determined we are the primary beneficiary. The primary beneficiary is the entity which has both: (1) the power to direct the activities of the VIE that most significantly impact the VIE’s economic performance and (2) the obligation to absorb losses or receive benefits of the entity that could potentially be significant to the VIE.
Recently Issued but Not Yet Adopted Accounting Pronouncements	Recently Issued and Adopted Accounting Pronouncements In November 2016, the Financial Accounting Standards Board (the “FASB”) issued Accounting Standards Update (“ASU”) No. 2016-18, “Statement of Cash Flows (Topic 230): Restricted Cash.” Whereas restricted cash balances have traditionally been excluded from the statement of cash flows, this ASU requires restricted cash and restricted cash equivalents to be included within the beginning and ending totals of cash, cash equivalents and restricted cash presented on the statement of cash flows for all periods presented. Restricted cash and restricted cash equivalent inflows and outflows with external parties are required to be classified within the operating, investing, and/or financing activity sections of the statement of cash flows, whereas transfers between cash and cash equivalents and restricted cash and restricted cash equivalents should no longer be presented on the statement of cash flows. ASU No. 2016-18 also requires (a) the nature of the restrictions to be disclosed to help provide information about the sources and uses of these balances during a reporting period and (b) a reconciliation of the cash, cash equivalents and restricted cash totals on the statement of cash flows to the related balance sheet line items when cash, cash equivalents, and restricted cash are presented in more than one line item on the balance sheet. The reconciliation can be presented either on the face of the statement of cash flows or in the notes to the financial statements and must be provided for each period that a balance sheet is presented. We adopted the new accounting pronouncement on January 1, 2018, and the adoption did not have a material impact to our statement of cash flows. In February 2018, the FASB issued ASU No. 2018-02, “Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income,” which allows a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the tax law and tax rate changes under the Tax Cuts and Jobs Act of 2017 (the “Tax Act”) enacted on December 22, 2017. Under the Tax Act, deferred taxes were adjusted to reflect the reduction of the historical corporate income tax rate to the newly enacted corporate income tax rate, which left the tax effects on items within accumulated other comprehensive income stranded at an inappropriate tax rate. This guidance is effective for fiscal years beginning after December 15, 2018, and for interim periods within those fiscal years, with early adoption permitted. We adopted this standard effective January 1, 2018 and recorded a $ 0.6 million reclass from accumulated other comprehensive income to retained earnings in the first quarter of 2018.

Loans Held for Investment (Tabl

Loans Held for Investment (Tables)	3 Months Ended
	Mar. 31, 2018
Receivables [Abstract]
Schedule of Accounts, Notes, Loans and Financing Receivable	Loans held for investment are summarized as follows: March 31, December 31, 2018 2017 Private Education Loans $ 18,794,012 $ 17,432,167 Deferred origination costs and unamortized premium/(discount) 58,814 56,378 Allowance for loan losses (252,103 ) (243,715 ) Total Private Education Loans, net 18,600,723 17,244,830 FFELP Loans 907,842 927,660 Deferred origination costs and unamortized premium/(discount) 2,566 2,631 Allowance for loan losses (1,113 ) (1,132 ) Total FFELP Loans, net 909,295 929,159 Personal Loans 675,656 400,280 Deferred origination costs and unamortized premium/(discount) (163 ) — Allowance for loan losses (18,907 ) (6,628 ) Total Personal Loans, net 656,586 393,652 Loans held for investment, net $ 20,166,604 $ 18,567,641 The average balance and the respective weighted average interest rates of loans in our portfolio are summarized as follows: Three Months Ended March 31, 2018 2017 Average Balance Weighted Average Interest Rate Average Balance Weighted Average Interest Rate Private Education Loans $ 18,659,717 8.84 % $ 15,449,555 8.26 % FFELP Loans 919,717 4.25 1,003,128 3.69 Personal Loans 528,644 10.64 35,830 9.16 Total portfolio $ 20,108,078 $ 16,488,513 The following table provides the average recorded investment and interest income recognized for our TDR loans. Three Months Ended 2018 2017 Average Recorded Investment Interest Income Recognized Average Recorded Investment Interest Income Recognized TDR Loans $ 1,032,232 $ 17,847 $ 669,606 $ 12,257

Allowance for Loan Losses (Tabl

Allowance for Loan Losses (Tables)	3 Months Ended
	Mar. 31, 2018
Receivables [Abstract]
Allowance for credit losses and recorded investments in loans	Allowance for Loan Losses Metrics Allowance for Loan Losses Three Months Ended March 31, 2018 FFELP Loans Private Education Loans Personal Loans Total Allowance for Loan Losses Beginning balance $ 1,132 $ 243,715 $ 6,628 $ 251,475 Total provision 231 41,870 13,448 55,549 Net charge-offs: Charge-offs (250 ) (37,353 ) (1,200 ) (38,803 ) Recoveries — 5,087 31 5,118 Net charge-offs (250 ) (32,266 ) (1,169 ) (33,685 ) Loan sales (1) — (1,216 ) — (1,216 ) Ending Balance $ 1,113 $ 252,103 $ 18,907 $ 272,123 Allowance: Ending balance: individually evaluated for impairment $ — $ 101,824 $ — $ 101,824 Ending balance: collectively evaluated for impairment $ 1,113 $ 150,279 $ 18,907 $ 170,299 Loans: Ending balance: individually evaluated for impairment $ — $ 1,043,103 $ — $ 1,043,103 Ending balance: collectively evaluated for impairment $ 907,842 $ 17,750,909 $ 675,656 $ 19,334,407 Net charge-offs as a percentage of average loans in repayment (annualized) (2) 0.14 % 1.01 % 0.88 % Allowance as a percentage of the ending total loan balance 0.12 % 1.34 % 2.80 % Allowance as a percentage of the ending loans in repayment (2) 0.16 % 1.95 % 2.80 % Allowance coverage of net charge-offs (annualized) 1.11 1.95 4.04 Ending total loans, gross $ 907,842 $ 18,794,012 $ 675,656 Average loans in repayment (2) $ 718,311 $ 12,747,929 $ 531,889 Ending loans in repayment (2) $ 702,965 $ 12,958,742 $ 675,656 ____________ (1) Represents fair value adjustments on loans sold. (2) Loans in repayment include loans on which borrowers are making interest only or fixed payments, as well as loans that have entered full principal and interest repayment status after any applicable grace period. Allowance for Loan Losses Three Months Ended March 31, 2017 FFELP Loans Private Education Loans Personal Loans Total Allowance for Loan Losses Beginning balance $ 2,171 $ 182,472 $ 58 $ 184,701 Total provision (316 ) 26,820 288 26,792 Net charge-offs: Charge-offs (218 ) (26,227 ) — (26,445 ) Recoveries — 3,259 — 3,259 Net charge-offs (218 ) (22,968 ) — (23,186 ) Loan sales (1) — (1,221 ) — (1,221 ) Ending Balance $ 1,637 $ 185,103 $ 346 $ 187,086 Allowance: Ending balance: individually evaluated for impairment $ — $ 87,150 $ — $ 87,150 Ending balance: collectively evaluated for impairment $ 1,637 $ 97,953 $ 346 $ 99,936 Loans: Ending balance: individually evaluated for impairment $ — $ 701,860 $ — $ 701,860 Ending balance: collectively evaluated for impairment $ 989,393 $ 14,952,994 $ 55,502 $ 15,997,889 Net charge-offs as a percentage of average loans in repayment (annualized) (2) 0.11 % 0.89 % — % Allowance as a percentage of the ending total loan balance 0.17 % 1.18 % 0.62 % Allowance as a percentage of the ending loans in repayment (2) 0.22 % 1.76 % 0.62 % Allowance coverage of net charge-offs (annualized) 1.88 2.01 — Ending total loans, gross $ 989,393 $ 15,654,854 $ 55,502 Average loans in repayment (2) $ 771,435 $ 10,265,530 $ 35,830 Ending loans in repayment (2) $ 757,052 $ 10,526,782 $ 55,502 ____________ (1) Represents fair value adjustments on loans sold. (2) Loans in repayment include loans on which borrowers are making interest only or fixed payments, as well as loans that have entered full principal and interest repayment status after any applicable grace period.
Impaired financing receivables	The following table provides the recorded investment, unpaid principal balance and related allowance for our TDR loans. Recorded Investment Unpaid Principal Balance Allowance March 31, 2018 TDR Loans $ 1,061,046 $ 1,043,103 $ 101,824 December 31, 2017 TDR Loans $ 1,007,141 $ 990,351 $ 94,682
Average recorded investment and interest income recognized for troubled debt restructuring loans	Loans held for investment are summarized as follows: March 31, December 31, 2018 2017 Private Education Loans $ 18,794,012 $ 17,432,167 Deferred origination costs and unamortized premium/(discount) 58,814 56,378 Allowance for loan losses (252,103 ) (243,715 ) Total Private Education Loans, net 18,600,723 17,244,830 FFELP Loans 907,842 927,660 Deferred origination costs and unamortized premium/(discount) 2,566 2,631 Allowance for loan losses (1,113 ) (1,132 ) Total FFELP Loans, net 909,295 929,159 Personal Loans 675,656 400,280 Deferred origination costs and unamortized premium/(discount) (163 ) — Allowance for loan losses (18,907 ) (6,628 ) Total Personal Loans, net 656,586 393,652 Loans held for investment, net $ 20,166,604 $ 18,567,641 The average balance and the respective weighted average interest rates of loans in our portfolio are summarized as follows: Three Months Ended March 31, 2018 2017 Average Balance Weighted Average Interest Rate Average Balance Weighted Average Interest Rate Private Education Loans $ 18,659,717 8.84 % $ 15,449,555 8.26 % FFELP Loans 919,717 4.25 1,003,128 3.69 Personal Loans 528,644 10.64 35,830 9.16 Total portfolio $ 20,108,078 $ 16,488,513 The following table provides the average recorded investment and interest income recognized for our TDR loans. Three Months Ended 2018 2017 Average Recorded Investment Interest Income Recognized Average Recorded Investment Interest Income Recognized TDR Loans $ 1,032,232 $ 17,847 $ 669,606 $ 12,257
Age analysis of past due loans delinquencies	The following table provides information regarding the loan status of our Private Education Loans. Loans in repayment include loans making interest only or fixed payments, as well as loans that have entered full principal and interest repayment status after any applicable grace period. Private Education Loans March 31, December 31, 2018 2017 Balance % Balance % Loans in-school/grace/deferment (1) $ 5,369,984 $ 4,757,732 Loans in forbearance (2) 465,286 468,402 Loans in repayment and percentage of each status: Loans current 12,635,627 97.5 % 11,911,128 97.6 % Loans delinquent 31-60 days (3) 179,989 1.4 179,002 1.5 Loans delinquent 61-90 days (3) 95,974 0.7 78,292 0.6 Loans delinquent greater than 90 days (3) 47,152 0.4 37,611 0.3 Total Private Education Loans in repayment 12,958,742 100.0 % 12,206,033 100.0 % Total Private Education Loans, gross 18,794,012 17,432,167 Private Education Loans deferred origination costs and unamortized premium/(discount) 58,814 56,378 Total Private Education Loans 18,852,826 17,488,545 Private Education Loans allowance for losses (252,103 ) (243,715 ) Private Education Loans, net $ 18,600,723 $ 17,244,830 Percentage of Private Education Loans in repayment 69.0 % 70.0 % Delinquencies as a percentage of Private Education Loans in repayment 2.5 % 2.4 % Loans in forbearance as a percentage of Private Education Loans in repayment and forbearance 3.5 % 3.7 % (1) Deferment includes customers who have returned to school or are engaged in other permitted educational activities and are not yet required to make payments on the loans (e.g., residency periods for medical students or a grace period for bar exam preparation). (2) Loans for customers who have requested extension of grace period generally during employment transition or who have temporarily ceased making full payments due to hardship or other factors, consistent with established loan program servicing policies and procedures. (3) The period of delinquency is based on the number of days scheduled payments are contractually past due. The following table provides information regarding the loan status and aging of TDR loans. March 31, December 31, 2018 2017 Balance % Balance % TDR loans in in-school/grace/deferment (1) $ 58,939 $ 51,745 TDR loans in forbearance (2) 65,036 69,652 TDR loans in repayment (3) and percentage of each status: Loans current 823,813 89.7 % 774,222 89.1 % Loans delinquent 31-60 days (4) 47,127 5.1 48,377 5.6 Loans delinquent 61-90 days (4) 31,463 3.4 28,778 3.3 Loans delinquent greater than 90 days (4) 16,725 1.8 17,577 2.0 Total TDR loans in repayment 919,128 100.0 % 868,954 100.0 % Total TDR loans, gross $ 1,043,103 $ 990,351 _____ (1) Deferment includes customers who have returned to school or are engaged in other permitted educational activities and are not yet required to make payments on the loans (e.g., residency periods for medical students or a grace period for bar exam preparation). (2) Loans for customers who have requested extension of grace period generally during employment transition or who have temporarily ceased making full payments due to hardship or other factors, consistent with established loan program servicing policies and procedures. (3) Loans in repayment include loans on which borrowers are making interest only or fixed payments, as well as loans that have entered full principal and interest repayment status after any applicable grace period. (4) The period of delinquency is based on the number of days scheduled payments are contractually past due.
Modified loans accounts for troubled debt restructuring	The following table provides the amount of modified loans (which include forbearance and reductions in interest rates) that became TDRs in the periods presented. Additionally, for the periods presented, the table summarizes charge-offs occurring in the TDR portfolio, as well as TDRs for which a payment default occurred in the relevant period presented and within 12 months of the loan first being designated as a TDR. We define payment default as more than 60 days past due for this disclosure. Three Months Ended Three Months Ended Modified Loans (1) Charge-offs Payment- Default Modified Loans (1) Charge-offs Payment- Default TDR Loans $ 84,174 $ 15,460 $ 29,757 $ 112,206 $ 10,523 $ 25,526 _____ (1) Represents the principal balance of loans that have been modified during the period and resulted in a TDR.
Private education loan portfolio stratified by key credit quality indicators	The following table highlights the gross principal balance of our Private Education Loan portfolio stratified by key credit quality indicators. Private Education Loans Credit Quality Indicators March 31, 2018 December 31, 2017 Credit Quality Indicators: Balance (1) % of Balance Balance (1) % of Balance Cosigners: With cosigner $ 16,889,477 90 % $ 15,658,539 90 % Without cosigner 1,904,535 10 1,773,628 10 Total $ 18,794,012 100 % $ 17,432,167 100 % FICO at Original Approval (2) : Less than 670 $ 1,257,596 6 % $ 1,153,591 6 % 670-699 2,810,526 15 2,596,959 15 700-749 6,168,342 33 5,714,554 33 Greater than or equal to 750 8,557,548 46 7,967,063 46 Total $ 18,794,012 100 % $ 17,432,167 100 % Seasoning (3) : 1-12 payments $ 4,754,416 25 % $ 4,256,592 24 % 13-24 payments 3,256,637 17 3,229,465 19 25-36 payments 2,492,490 13 2,429,238 14 37-48 payments 1,583,375 9 1,502,327 9 More than 48 payments 1,337,110 7 1,256,813 7 Not yet in repayment 5,369,984 29 4,757,732 27 Total $ 18,794,012 100 % $ 17,432,167 100 % (1) Balance represents gross Private Education Loans. (2) Represents the higher credit score of the cosigner or the borrower. (3) Number of months in active repayment (whether interest only payment, fixed payment, or full principal and interest payment status) for which a scheduled payment was due. The following table highlights the gross principal balance of our Personal Loan portfolio stratified by key credit quality indicators. Personal Loans Credit Quality Indicators March 31, 2018 December 31, 2017 Credit Quality Indicators: Balance (1) % of Balance Balance (1) % of Balance FICO at Original Approval: Less than 670 $ 52,417 8 % $ 32,156 8 % 670-699 193,246 29 114,731 29 700-749 307,539 45 182,025 45 Greater than or equal to 750 122,454 18 71,368 18 Total $ 675,656 100 % $ 400,280 100 % Seasoning (2) : 0-12 payments $ 649,996 96 % $ 400,280 100 % 13-24 payments 25,660 4 — — 25-36 payments — — — — 37-48 payments — — — — More than 48 payments — — — — Total $ 675,656 100 % $ 400,280 100 % (1) Balance represents gross Personal Loans. (2) Number of months in active repayment for which a scheduled payment was due.
Accrued interest receivable	The following table provides information regarding accrued interest receivable on our Private Education Loans. The table also discloses the amount of accrued interest on loans greater than 90 days past due as compared to our allowance for uncollectible interest. The allowance for uncollectible interest exceeds the amount of accrued interest on our 90 days past due Private Education Loan portfolio for all periods presented. Private Education Loans Accrued Interest Receivable Total Interest Receivable Greater Than 90 Days Past Due Allowance for Uncollectible Interest March 31, 2018 $ 1,045,577 $ 1,783 $ 4,694 December 31, 2017 $ 951,138 $ 1,372 $ 4,664

Deposits (Tables)

Deposits (Tables)	3 Months Ended
	Mar. 31, 2018
Banking and Thrift [Abstract]
Schedule of deposits	The following table summarizes total deposits at March 31, 2018 and December 31, 2017 . March 31, December 31, 2018 2017 Deposits - interest bearing $ 16,497,006 $ 15,504,330 Deposits - non-interest bearing 1,640 1,053 Total deposits $ 16,498,646 $ 15,505,383
Interest bearing deposits	Interest bearing deposits at March 31, 2018 and December 31, 2017 are summarized as follows: March 31, 2018 December 31, 2017 Amount Qtr.-End Weighted Average Stated Rate (1) Amount Year-End Weighted Average Stated Rate (1) Money market $ 8,107,996 2.01 % $ 7,731,966 1.80 % Savings 681,024 1.40 738,243 1.10 Certificates of deposit 7,707,986 2.13 7,034,121 1.93 Deposits - interest bearing $ 16,497,006 $ 15,504,330 ____________ (1) Includes the effect of interest rate swaps in effective hedge relationships.

Borrowings (Tables)

Borrowings (Tables)	3 Months Ended
	Mar. 31, 2018
Debt Disclosure [Abstract]
Schedule of debt	The following table summarizes our borrowings at March 31, 2018 and December 31, 2017 . March 31, 2018 December 31, 2017 Short-Term Long-Term Total Short-Term Long-Term Total Unsecured borrowings: Unsecured debt $ — $ 196,741 $ 196,741 $ — $ 196,539 $ 196,539 Total unsecured borrowings — 196,741 196,741 — 196,539 196,539 Secured borrowings: Private Education Loan term securitizations — 3,547,604 3,547,604 — 3,078,731 3,078,731 ABCP Facility — — — — — — Total secured borrowings — 3,547,604 3,547,604 — 3,078,731 3,078,731 Total $ — $ 3,744,345 $ 3,744,345 $ — $ 3,275,270 $ 3,275,270
Schedule of securities financing transactions	Secured Financings at Issuance Issue Date Issued Total Issued Weighted Average Cost of Funds (1) Weighted Average Life (in years) Private Education: 2016-A May 2016 $ 501,000 1-month LIBOR plus 1.38% 4.01 2016-B July 2016 607,000 1-month LIBOR plus 1.36% 4.01 2016-C October 2016 674,000 1-month LIBOR plus 1.15% 4.27 Total notes issued in 2016 $ 1,782,000 Total loan and accrued interest amount securitized at inception in 2016 $ 2,107,042 2017-A February 2017 $ 772,000 1-month LIBOR plus 0.93% 4.27 2017-B November 2017 676,000 1-month LIBOR plus 0.80% 4.07 Total notes issued in 2017 $ 1,448,000 Total loan and accrued interest amount securitized at inception in 2017 $ 1,606,804 2018-A March 2018 $ 670,000 1-month LIBOR plus 0.78% 4.43 Total notes issued in 2018 $ 670,000 Total loan and accrued interest amount securitized at inception in 2018 $ 744,917 ____________ (1) Represents LIBOR equivalent cost of funds for floating and fixed rate bonds, excluding issuance costs.
Schedule of variable interest entities	We consolidate the following financing VIEs as of March 31, 2018 and December 31, 2017 , respectively: March 31, 2018 Debt Outstanding Carrying Amount of Assets Securing Debt Outstanding Short-Term Long-Term Total Loans Restricted Cash Other Assets (1) Total Secured borrowings: Private Education Loan term securitizations $ — $ 3,547,604 $ 3,547,604 $ 4,243,820 $ 106,351 $ 280,646 $ 4,630,817 ABCP Facility — — — — 8,658 9,884 18,542 Total $ — $ 3,547,604 $ 3,547,604 $ 4,243,820 $ 115,009 $ 290,530 $ 4,649,359 December 31, 2017 Debt Outstanding Carrying Amount of Assets Securing Debt Outstanding Short-Term Long-Term Total Loans Restricted Cash Other Assets (1) Total Secured borrowings: Private Education Loan term securitizations $ — $ 3,078,731 $ 3,078,731 $ 3,691,024 $ 95,966 $ 240,208 $ 4,027,198 ABCP Facility — — — — 1,017 161 1,178 Total $ — $ 3,078,731 $ 3,078,731 $ 3,691,024 $ 96,983 $ 240,369 $ 4,028,376 ____ (1) Other assets primarily represent accrued interest receivable.

Derivative Financial Instrume26

Derivative Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Impact of derivatives on the consolidated balance sheet	The following tables summarize the fair values and notional amounts of all derivative instruments at March 31, 2018 and December 31, 2017 , and their impact on earnings and other comprehensive income for the three months ended March 31, 2018 and 2017. Please refer to Note 11, “Derivative Financial Instruments” in our 2017 Form 10-K for a full discussion of cash flow hedges, fair value hedges, and trading activities. Impact of Derivatives on the Consolidated Balance Sheet Cash Flow Hedges Fair Value Hedges Trading Total March 31, December 31, March 31, December March 31, December March 31, December 2018 2017 2018 2017 2018 2017 2018 2017 Fair Values (1) Hedged Risk Exposure Derivative Assets: (2) Interest rate swaps Interest rate $ — $ — $ 794 $ 630 $ — $ 182 $ 794 $ 812 Derivative Liabilities: (2) Interest rate swaps Interest rate (1,053 ) (2,584 ) — — (36 ) — (1,089 ) (2,584 ) Total net derivatives $ (1,053 ) $ (2,584 ) $ 794 $ 630 $ (36 ) $ 182 $ (295 ) $ (1,772 ) ___________ (1) Fair values reported include variation margin as legal settlement of the derivative contract and accrued interest. Assets and liabilities are presented without consideration of master netting agreements. Derivatives are carried on the balance sheet based on net position by counterparty under master netting agreements, and classified in other assets or other liabilities depending on whether in a net positive or negative position. (2) The following table reconciles gross positions with the impact of master netting agreements to the balance sheet classification: Other Assets Other Liabilities March 31, December 31, March 31, December 31, 2018 2017 2018 2017 Gross position (1) $ 794 $ 812 $ (1,089 ) $ (2,584 ) Impact of master netting agreement (794 ) (812 ) 794 812 Derivative values with impact of master netting agreements (as carried on balance sheet) — — (295 ) (1,772 ) Cash collateral pledged (2) — — 31,637 21,586 Net position $ — $ — $ 31,342 $ 19,814 __________ (1) Gross position amounts include accrued interest and variation margin as legal settlement of the derivative contract. (2) Cash collateral pledged excludes amounts that represent legal settlement of the derivative contracts.
Offsetting assets	The following table reconciles gross positions with the impact of master netting agreements to the balance sheet classification: Other Assets Other Liabilities March 31, December 31, March 31, December 31, 2018 2017 2018 2017 Gross position (1) $ 794 $ 812 $ (1,089 ) $ (2,584 ) Impact of master netting agreement (794 ) (812 ) 794 812 Derivative values with impact of master netting agreements (as carried on balance sheet) — — (295 ) (1,772 ) Cash collateral pledged (2) — — 31,637 21,586 Net position $ — $ — $ 31,342 $ 19,814 __________ (1) Gross position amounts include accrued interest and variation margin as legal settlement of the derivative contract. (2) Cash collateral pledged excludes amounts that represent legal settlement of the derivative contracts.
Offsetting liabilities	The following table reconciles gross positions with the impact of master netting agreements to the balance sheet classification: Other Assets Other Liabilities March 31, December 31, March 31, December 31, 2018 2017 2018 2017 Gross position (1) $ 794 $ 812 $ (1,089 ) $ (2,584 ) Impact of master netting agreement (794 ) (812 ) 794 812 Derivative values with impact of master netting agreements (as carried on balance sheet) — — (295 ) (1,772 ) Cash collateral pledged (2) — — 31,637 21,586 Net position $ — $ — $ 31,342 $ 19,814 __________ (1) Gross position amounts include accrued interest and variation margin as legal settlement of the derivative contract. (2) Cash collateral pledged excludes amounts that represent legal settlement of the derivative contracts.
Schedule of notional amounts of outstanding derivative positions	Cash Flow Fair Value Derivatives Not Designated as Hedges Total March 31, December 31, March 31, December 31, March 31, December 31, March 31, December 31, 2018 2017 2018 2017 2018 2017 2018 2017 Notional Values Interest rate swaps $ 1,376,816 $ 1,408,649 $ 3,867,204 $ 3,062,849 $ 1,161,000 $ 987,577 $ 6,405,020 $ 5,459,075 Other (1) $ — $ — $ — $ — $ 5,476 $ 3,245 $ 5,476 $ 3,245
Derivative instruments, gain (loss)	Impact of Derivatives on the Consolidated Statements of Income Three Months Ended 2018 2017 Fair Value Hedges Interest rate swaps: Hedge ineffectiveness realized gains (losses) recorded in earnings (1) $ 5,853 $ (4,167 ) Realized gains (losses) recorded in interest expense (514 ) 4,547 Total $ 5,339 $ 380 Cash Flow Hedges Interest rate swaps: Hedge ineffectiveness gains (losses) recorded in earnings (1) $ 2,684 $ (72 ) Realized losses recorded in interest expense (1,562 ) (3,339 ) Total $ 1,122 $ (3,411 ) Trading Interest rate swaps: Interest reclassification $ 110 $ 80 Realized losses recorded in earnings (4,755 ) (1,219 ) Total (1) (4,645 ) (1,139 ) Total $ 1,816 $ (4,170 ) ________ (1) Amounts included in “gains (losses) on derivatives and hedging activities, net” in the consolidated statements of income.
Schedule of derivative instruments, effect on other comprehensive income (loss)	Impact of Derivatives on the Statements of Changes in Stockholders’ Equity Three Months Ended March 31, 2018 2017 Amount of gain recognized in other comprehensive income (loss) $ 18,728 $ 1,440 Less: amount of loss reclassified in interest expense (1) (1,562 ) (3,339 ) Total change in other comprehensive income (loss) for unrealized gains on derivatives, before income tax (expense) benefit $ 20,290 $ 4,779 ___________ (1) Amounts included in “realized losses recorded in interest expense” in the “Impact of Derivatives on the Consolidated Statements of Income” table.

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	3 Months Ended
	Mar. 31, 2018
Equity [Abstract]
Schedule of common share repurchases	The following table summarizes our common share repurchases and issuances. Three Months Ended (Shares and per share amounts in actuals) 2018 2017 Shares repurchased related to employee stock-based compensation plans (1)(2) 2,740,018 1,603,487 Average purchase price per share $ 11.31 $ 11.96 Common shares issued (3) 5,559,991 3,738,717 __________________ (1) Comprised of shares withheld from stock option exercises and vesting of restricted stock for employees’ tax withholding obligations and shares tendered by employees to satisfy option exercise costs. (2) At the present time, we do not intend to initiate a publicly announced share repurchase program. (3) Common shares issued under our various compensation and benefit plans.

Earnings per Common Share (Tabl

Earnings per Common Share (Tables)	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Schedule of earnings per share, basic and diluted	A reconciliation of the numerators and denominators of the basic and diluted EPS calculations follows. Three Months Ended March 31, (In thousands, except per share data) 2018 2017 Numerator: Net income $ 126,254 $ 94,943 Preferred stock dividends 3,397 5,575 Net income attributable to SLM Corporation common stock $ 122,857 $ 89,368 Denominator: Weighted average shares used to compute basic EPS 433,952 429,891 Effect of dilutive securities: Dilutive effect of stock options, restricted stock, restricted stock units and Employee Stock Purchase Plan (“ESPP”) (1)(2) 5,025 8,844 Weighted average shares used to compute diluted EPS 438,977 438,735 Basic earnings per common share attributable to SLM Corporation $ 0.28 $ 0.21 Diluted earnings per common share attributable to SLM Corporation $ 0.28 $ 0.20 ________________ (1) Includes the potential dilutive effect of additional common shares that are issuable upon exercise of outstanding stock options, restricted stock, restricted stock units, and the outstanding commitment to issue shares under the ESPP, determined by the treasury stock method. (2) For the three months ended March 31, 2018 and 2017, securities covering approximately 0 and 0 shares, respectively, were outstanding but not included in the computation of diluted earnings per share because they were anti-dilutive.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Valuation of financial instruments that are marked-to-market on recurring basis	The following table summarizes the valuation of our financial instruments that are marked to fair value on a recurring basis. Fair Value Measurements on a Recurring Basis March 31, 2018 December 31, 2017 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets Available-for-sale investments $ — $ 229,114 $ — $ 229,114 $ — $ 244,088 $ — $ 244,088 Derivative instruments — 794 — 794 — 812 — 812 Total $ — $ 229,908 $ — $ 229,908 $ — $ 244,900 $ — $ 244,900 Liabilities Derivative instruments $ — $ (1,089 ) $ — $ (1,089 ) $ — $ (2,584 ) $ — $ (2,584 ) Total $ — $ (1,089 ) $ — $ (1,089 ) $ — $ (2,584 ) $ — $ (2,584 )
Fair values of financial assets and liabilities, including derivative financial instruments	The following table summarizes the fair values of our financial assets and liabilities, including derivative financial instruments. March 31, 2018 December 31, 2017 Fair Value Carrying Value Difference Fair Value Carrying Value Difference Earning assets Loans held for investment, net $ 22,264,191 $ 20,166,604 $ 2,097,587 $ 20,673,136 $ 18,567,641 $ 2,105,495 Cash and cash equivalents 1,435,649 1,435,649 — 1,534,339 1,534,339 — Available-for-sale investments 229,114 229,114 — 244,088 244,088 — Accrued interest receivable 1,063,449 1,063,449 — 967,482 967,482 — Tax indemnification receivable 169,242 169,242 — 168,011 168,011 — Derivative instruments 794 794 — 812 812 — Total earning assets $ 25,162,439 $ 23,064,852 $ 2,097,587 $ 23,587,868 $ 21,482,373 $ 2,105,495 Interest-bearing liabilities Money-market and savings accounts $ 8,789,020 $ 8,789,020 $ — $ 8,470,209 $ 8,470,209 $ — Certificates of deposit 8,095,950 7,707,986 (387,964 ) 7,044,208 7,034,121 (10,087 ) Long-term borrowings 3,731,696 3,744,345 12,649 3,299,871 3,275,270 (24,601 ) Accrued interest payable 46,396 46,396 — 35,363 35,363 — Derivative instruments 1,089 1,089 — 2,584 2,584 — Total interest-bearing liabilities $ 20,664,151 $ 20,288,836 $ (375,315 ) $ 18,852,235 $ 18,817,547 $ (34,688 ) Excess of net asset fair value over carrying value $ 1,722,272 $ 2,070,807

Regulatory Capital (Tables)

Regulatory Capital (Tables)	3 Months Ended
	Mar. 31, 2018
Banking and Thrift [Abstract]
Schedule of compliance with regulatory capital requirements under banking regulations	The following capital amounts and ratios are based upon the Bank’s assets. Actual “Well Capitalized” Amount Ratio Amount Ratio As of March 31, 2018: Common Equity Tier 1 Capital (to Risk-Weighted Assets) $ 2,494,964 11.7 % $ 1,385,322 > 6.5 % Tier 1 Capital (to Risk-Weighted Assets) $ 2,494,964 11.7 % $ 1,705,011 > 8.0 % Total Capital (to Risk-Weighted Assets) $ 2,761,446 13.0 % $ 2,131,264 > 10.0 % Tier 1 Capital (to Average Assets) $ 2,494,964 11.0 % $ 1,138,524 > 5.0 % As of December 31, 2017: Common Equity Tier 1 Capital (to Risk-Weighted Assets) $ 2,350,081 11.9 % $ 1,288,435 > 6.5 % Tier 1 Capital (to Risk-Weighted Assets) $ 2,350,081 11.9 % $ 1,585,767 > 8.0 % Total Capital (to Risk-Weighted Assets) $ 2,597,926 13.1 % $ 1,982,208 > 10.0 % Tier 1 Capital (to Average Assets) $ 2,350,081 11.0 % $ 1,067,739 > 5.0 %

Significant Accounting Polices

Significant Accounting Polices - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018USD ($)
Accounting Policies [Abstract]
Reclassification from accumulated other comprehensive income to retained earnings resulting from tax cuts and jobs act	$ 0.6

Loans Held for Investment - Add

Loans Held for Investment - Additional Information (Detail)	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jul. 01, 2006	Jun. 30, 2006	Sep. 30, 1993
Receivables [Abstract]
Percent of private loans indexed to LIBOR	74.00%		77.00%
Tier 1 of government guarantee (in percentage)	97.00%			97.00%
Tier 2 of government guarantee (in percentage)					98.00%
Tier 3 of government guarantee (in percentage)						100.00%
Estimated weighted average life of student loans (in years)	5 years 5 months 5 days	5 years 6 months 5 days

Loans Held for Investment - Stu

Loans Held for Investment - Student Loan Portfolio by Program (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	$ (272,123)	$ (251,475)	$ (187,086)	$ (184,701)
Loans held for investment, net	20,166,604	18,567,641
Private Education Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Private Education Loans	18,794,012	17,432,167
Deferred origination costs and unamortized premium/(discount)	58,814	56,378
Allowance for loan losses	(252,103)	(243,715)
Loans held for investment, net	18,600,723	17,244,830
FFELP Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Private Education Loans	907,842	927,660
Deferred origination costs and unamortized premium/(discount)	2,566	2,631
Allowance for loan losses	(1,113)	(1,132)
Loans held for investment, net	909,295	929,159
Personal Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Private Education Loans	675,656	400,280
Deferred origination costs and unamortized premium/(discount)	(163)	0
Allowance for loan losses	(18,907)	(6,628)
Loans held for investment, net	$ 656,586	$ 393,652

Loans Held for Investment - S34

Loans Held for Investment - Student Loan Portfolio Average Balances (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average Balance	$ 20,108,078		$ 16,488,513
Private Education Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average Balance	$ 18,659,717		15,449,555
Weighted Average Interest Rate	8.84%	8.26%
FFELP Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average Balance	$ 919,717		1,003,128
Weighted Average Interest Rate	4.25%	3.69%
Personal Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average Balance	$ 528,644		$ 35,830
Weighted Average Interest Rate	10.64%	9.16%

Allowance for Loan Losses - All

Allowance for Loan Losses - Allowance for Credit Losses and Recorded Investments in Loans (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)charge_off	Mar. 31, 2017USD ($)charge_off
Allowance for Loan Losses
Allowance at beginning of period	$ 251,475	$ 184,701
Total provision	55,549	26,792
Net charge-offs:
Charge-offs	(38,803)	(26,445)
Recoveries	5,118	3,259
Net charge-offs	(33,685)	(23,186)
Loan sales	(1,216)	(1,221)
Allowance at end of period	272,123	187,086
Allowance:
Ending balance: individually evaluated for impairment	101,824	87,150
Ending balance: collectively evaluated for impairment	170,299	99,936
Loans:
Ending balance: individually evaluated for impairment	1,043,103	701,860
Ending balance: collectively evaluated for impairment	19,334,407	15,997,889
FFELP Loans
Allowance for Loan Losses
Allowance at beginning of period	1,132	2,171
Total provision	231	(316)
Net charge-offs:
Charge-offs	(250)	(218)
Recoveries	0	0
Net charge-offs	(250)	(218)
Loan sales	0	0
Allowance at end of period	1,113	1,637
Allowance:
Ending balance: individually evaluated for impairment	0	0
Ending balance: collectively evaluated for impairment	1,113	1,637
Loans:
Ending balance: individually evaluated for impairment	0	0
Ending balance: collectively evaluated for impairment	$ 907,842	$ 989,393
Net charge-offs as a percentage of average loans in repayment (annualized)	0.14%	0.11%
Allowance as a percentage of the ending total loan balance	0.12%	0.17%
Allowance as a percentage of the ending loans in repayment	0.16%	0.22%
Allowance coverage of net charge-offs (annualized) | charge_off	1.11	1.88
Ending total loans, gross	$ 907,842	$ 989,393
Average loans in repayment	718,311	771,435
Ending loans in repayment	702,965	757,052
Private Education Loans
Allowance for Loan Losses
Allowance at beginning of period	243,715	182,472
Total provision	41,870	26,820
Net charge-offs:
Charge-offs	(37,353)	(26,227)
Recoveries	5,087	3,259
Net charge-offs	(32,266)	(22,968)
Loan sales	(1,216)	(1,221)
Allowance at end of period	252,103	185,103
Allowance:
Ending balance: individually evaluated for impairment	101,824	87,150
Ending balance: collectively evaluated for impairment	150,279	97,953
Loans:
Ending balance: individually evaluated for impairment	1,043,103	701,860
Ending balance: collectively evaluated for impairment	$ 17,750,909	$ 14,952,994
Net charge-offs as a percentage of average loans in repayment (annualized)	1.01%	0.89%
Allowance as a percentage of the ending total loan balance	1.34%	1.18%
Allowance as a percentage of the ending loans in repayment	1.95%	1.76%
Allowance coverage of net charge-offs (annualized) | charge_off	1.95	2.01
Ending total loans, gross	$ 18,794,012	$ 15,654,854
Average loans in repayment	12,747,929	10,265,530
Ending loans in repayment	12,958,742	10,526,782
Personal Loans
Allowance for Loan Losses
Allowance at beginning of period	6,628	58
Total provision	13,448	288
Net charge-offs:
Charge-offs	(1,200)	0
Recoveries	31	0
Net charge-offs	(1,169)
Loan sales	0	0
Allowance at end of period	18,907	346
Allowance:
Ending balance: individually evaluated for impairment	0	0
Ending balance: collectively evaluated for impairment	18,907	346
Loans:
Ending balance: individually evaluated for impairment	0	0
Ending balance: collectively evaluated for impairment	$ 675,656	$ 55,502
Net charge-offs as a percentage of average loans in repayment (annualized)	0.88%	0.00%
Allowance as a percentage of the ending total loan balance	2.80%	0.62%
Allowance as a percentage of the ending loans in repayment	2.80%	0.62%
Allowance coverage of net charge-offs (annualized) | charge_off	4.04	0
Ending total loans, gross	$ 675,656	$ 55,502
Average loans in repayment	531,889	35,830
Ending loans in repayment	$ 675,656	$ 55,502

Allowance for Loan Losses - Add

Allowance for Loan Losses - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Jul. 01, 2006
Receivables [Abstract]
Percentage of loans granted forbearance qualified as TDR	62.00%	66.00%
Criteria for loans to be considered as nonperforming (greater than)	90 days
Tier 1 of government guarantee (at least) (in percentage)	97.00%		97.00%
TDR payment default period (more than)	60 days
Percentage of FFELP loans insured and guaranteed (at least)	97.00%
Period of loans past due that have accrued interest (greater than)	90 days

Allowance for Loan Losses - Rec

Allowance for Loan Losses - Recorded Investment, Unpaid Principal Balance and Related Allowance for TDR Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Receivables [Abstract]
Recorded Investment	$ 1,061,046	$ 1,007,141
Unpaid Principal Balance	1,043,103	990,351
Allowance	$ 101,824	$ 94,682

Allowance for Loan Losses - Ave

Allowance for Loan Losses - Average Recorded Investment and Interest Income Recognized for TDR (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Receivables [Abstract]
Average Recorded Investment	$ 1,032,232	$ 669,606
Interest Income Recognized	$ 17,847	$ 12,257

Allowance for Loan Losses - Loa

Allowance for Loan Losses - Loan Status and Aging of Past Due TDR Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
TDR loans in repayment and percentage of each status:
Loans held for investment, net	$ 20,166,604	$ 18,567,641
Allowance for loan losses	(272,123)	(251,475)	$ (187,086)	$ (184,701)
Student Loan | Consumer Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
TDR loans in in-school/grace/deferment	5,369,984	4,757,732
TDR loans in forbearance	465,286	468,402
TDR loans in repayment and percentage of each status:
Loans current	12,635,627	11,911,128
Total TDR loans in repayment	$ 12,958,742	$ 12,206,033
Loans current (as a percentage)	97.50%	97.60%
Total TDR loans in repayment	100.00%	100.00%
Loans Gross	$ 18,794,012	$ 17,432,167
Private Education Loans deferred origination costs	58,814	56,378
Loans and Leases Receivable, before Fees, Gross	18,852,826	17,488,545
Loans held for investment, net	18,600,723	17,244,830
Allowance for loan losses	$ (252,103)	$ (243,715)
Percentage of Private Education Loans in repayment	69.00%	70.00%
Delinquencies as a percentage of Private Education Loans in repayment	2.50%	2.40%
Loans in forbearance as a percentage of Private Education Loans in repayment and forbearance	3.50%	3.70%
Student Loan | Consumer Portfolio Segment | Troubled Debt Restructured Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
TDR loans in in-school/grace/deferment	$ 58,939	$ 51,745
TDR loans in forbearance	65,036	69,652
TDR loans in repayment and percentage of each status:
Loans current	823,813	774,222
Total TDR loans in repayment	$ 919,128	$ 868,954
Loans current (as a percentage)	89.70%	89.10%
Total TDR loans in repayment	100.00%	100.00%
Total Private Education Loans	$ 1,043,103	$ 990,351
Student Loan | Consumer Portfolio Segment | Loans delinquent 31-60 days
TDR loans in repayment and percentage of each status:
Loans delinquent	$ 179,989	$ 179,002
Loans delinquent (as a percentage)	1.40%	1.50%
Student Loan | Consumer Portfolio Segment | Loans delinquent 31-60 days | Troubled Debt Restructured Loans
TDR loans in repayment and percentage of each status:
Loans delinquent	$ 47,127	$ 48,377
Loans delinquent (as a percentage)	5.10%	5.60%
Student Loan | Consumer Portfolio Segment | Loans delinquent 61-90 days
TDR loans in repayment and percentage of each status:
Loans delinquent	$ 95,974	$ 78,292
Loans delinquent (as a percentage)	0.70%	0.60%
Student Loan | Consumer Portfolio Segment | Loans delinquent 61-90 days | Troubled Debt Restructured Loans
TDR loans in repayment and percentage of each status:
Loans delinquent	$ 31,463	$ 28,778
Loans delinquent (as a percentage)	3.40%	3.30%
Student Loan | Consumer Portfolio Segment | Loans delinquent, greater than 90 days
TDR loans in repayment and percentage of each status:
Loans delinquent	$ 47,152	$ 37,611
Loans delinquent (as a percentage)	0.40%	0.30%
Student Loan | Consumer Portfolio Segment | Loans delinquent, greater than 90 days | Troubled Debt Restructured Loans
TDR loans in repayment and percentage of each status:
Loans delinquent	$ 16,725	$ 17,577
Loans delinquent (as a percentage)	1.80%	2.00%

Allowance for Loan Losses - Mod

Allowance for Loan Losses - Modified Loan Accounts for TDR (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Receivables [Abstract]
Modified Loans	$ 84,174	$ 112,206
Charge-offs	15,460	10,523
Payment Default	$ 29,757	$ 25,526

Allowance for Loan Losses - L41

Allowance for Loan Losses - Loan Portfolio Stratified by Key Credit Quality Indicators (Detail) - Consumer Portfolio Segment - Student Loan - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Private Education Loans | With Cosigner
Accounts, Notes, Loans and Financing Receivable [Line Items]
Private Education Loans	$ 16,889,477	$ 15,658,539
Private Education Loans with cosigner (in percentage)	90.00%	90.00%
Private Education Loans | Without Cosigner
Accounts, Notes, Loans and Financing Receivable [Line Items]
Private Education Loans	$ 1,904,535	$ 1,773,628
Private Education Loans without cosigner (in percentage)	10.00%	10.00%
Private Education Loans | Cosigners
Accounts, Notes, Loans and Financing Receivable [Line Items]
Private Education Loans	$ 18,794,012	$ 17,432,167
Total in percent	100.00%	100.00%
Private Education Loans | FICO at Original Approval
Accounts, Notes, Loans and Financing Receivable [Line Items]
Private Education Loans	$ 18,794,012	$ 17,432,167
Total in percent	100.00%	100.00%
Private Education Loans | Seasoning
Accounts, Notes, Loans and Financing Receivable [Line Items]
Private Education Loans	$ 18,794,012	$ 17,432,167
Total in percent	100.00%	100.00%
Seasoning based on monthly scheduled payments due from 1-12 payments (in percentage)	25.00%	24.00%
Seasoning based on monthly scheduled payments due from 13 - 24 payments (in percentage)	17.00%	19.00%
Seasoning based on monthly scheduled payments due from 25 - 36 payments (in percentage)	13.00%	14.00%
Seasoning based on monthly scheduled payments due from 37 - 48 payments (in percentage)	9.00%	9.00%
Seasoning based on monthly scheduled payments due from more than 48 payments (in percentage)	7.00%	7.00%
Seasoning based on monthly scheduled payments due from not yet in repayment (in percentage)	29.00%	27.00%
Private Education Loans | FICO score less than 670 | FICO at Original Approval
Accounts, Notes, Loans and Financing Receivable [Line Items]
Private Education Loans	$ 1,257,596	$ 1,153,591
Private Education Loans At Origination	6.00%	6.00%
Private Education Loans | FICO score 670-699 | FICO at Original Approval
Accounts, Notes, Loans and Financing Receivable [Line Items]
Private Education Loans	$ 2,810,526	$ 2,596,959
Private Education Loans At Origination	15.00%	15.00%
Private Education Loans | FICO score 700-749 | FICO at Original Approval
Accounts, Notes, Loans and Financing Receivable [Line Items]
Private Education Loans	$ 6,168,342	$ 5,714,554
Private Education Loans At Origination	33.00%	33.00%
Private Education Loans | FICO score greater than or equal to 750 | FICO at Original Approval
Accounts, Notes, Loans and Financing Receivable [Line Items]
Private Education Loans	$ 8,557,548	$ 7,967,063
Private Education Loans At Origination	46.00%	46.00%
Private Education Loans | 1-12 payments | Seasoning
Accounts, Notes, Loans and Financing Receivable [Line Items]
Private Education Loans	$ 4,754,416	$ 4,256,592
Private Education Loans | 13-24 payments | Seasoning
Accounts, Notes, Loans and Financing Receivable [Line Items]
Private Education Loans	3,256,637	3,229,465
Private Education Loans | 25-36 payments | Seasoning
Accounts, Notes, Loans and Financing Receivable [Line Items]
Private Education Loans	2,492,490	2,429,238
Private Education Loans | 37-48 payments | Seasoning
Accounts, Notes, Loans and Financing Receivable [Line Items]
Private Education Loans	1,583,375	1,502,327
Private Education Loans | More than 48 payments | Seasoning
Accounts, Notes, Loans and Financing Receivable [Line Items]
Private Education Loans	1,337,110	1,256,813
Private Education Loans | Not yet in repayment | Seasoning
Accounts, Notes, Loans and Financing Receivable [Line Items]
Private Education Loans	5,369,984	4,757,732
Personal Loans | FICO at Original Approval
Accounts, Notes, Loans and Financing Receivable [Line Items]
Private Education Loans	$ 675,656	$ 400,280
Total in percent	100.00%	100.00%
Personal Loans | Seasoning
Accounts, Notes, Loans and Financing Receivable [Line Items]
Private Education Loans	$ 675,656	$ 400,280
Total in percent	100.00%	100.00%
Seasoning based on monthly scheduled payments due from 1-12 payments (in percentage)	96.00%	100.00%
Seasoning based on monthly scheduled payments due from 13 - 24 payments (in percentage)	4.00%	0.00%
Seasoning based on monthly scheduled payments due from 25 - 36 payments (in percentage)	0.00%	0.00%
Seasoning based on monthly scheduled payments due from 37 - 48 payments (in percentage)	0.00%	0.00%
Seasoning based on monthly scheduled payments due from more than 48 payments (in percentage)	0.00%	0.00%
Personal Loans | FICO score less than 670 | FICO at Original Approval
Accounts, Notes, Loans and Financing Receivable [Line Items]
Private Education Loans	$ 52,417	$ 32,156
Private Education Loans At Origination	8.00%	8.00%
Personal Loans | FICO score 670-699 | FICO at Original Approval
Accounts, Notes, Loans and Financing Receivable [Line Items]
Private Education Loans	$ 193,246	$ 114,731
Private Education Loans At Origination	29.00%	29.00%
Personal Loans | FICO score 700-749 | FICO at Original Approval
Accounts, Notes, Loans and Financing Receivable [Line Items]
Private Education Loans	$ 307,539	$ 182,025
Private Education Loans At Origination	45.00%	45.00%
Personal Loans | FICO score greater than or equal to 750 | FICO at Original Approval
Accounts, Notes, Loans and Financing Receivable [Line Items]
Private Education Loans	$ 122,454	$ 71,368
Private Education Loans At Origination	18.00%	18.00%
Personal Loans | 1-12 payments | Seasoning
Accounts, Notes, Loans and Financing Receivable [Line Items]
Private Education Loans	$ 649,996	$ 400,280
Personal Loans | 13-24 payments | Seasoning
Accounts, Notes, Loans and Financing Receivable [Line Items]
Private Education Loans	25,660	0
Personal Loans | 25-36 payments | Seasoning
Accounts, Notes, Loans and Financing Receivable [Line Items]
Private Education Loans	0	0
Personal Loans | 37-48 payments | Seasoning
Accounts, Notes, Loans and Financing Receivable [Line Items]
Private Education Loans	0	0
Personal Loans | More than 48 payments | Seasoning
Accounts, Notes, Loans and Financing Receivable [Line Items]
Private Education Loans	$ 0	$ 0

Allowance for Loan Losses - Age

Allowance for Loan Losses - Age Analysis of Past Due Loans Delinquencies (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Loans in repayment and percentage of each status:
Private Education Loans allowance for losses	$ (272,123)	$ (251,475)	$ (187,086)	$ (184,701)
Loans held for investment, net	20,166,604	18,567,641
Private Education Loans
Loans in repayment and percentage of each status:
Total Private Education Loans, gross	18,794,012	17,432,167
Private Education Loans deferred origination costs	58,814	56,378
Private Education Loans allowance for losses	(252,103)	(243,715)
Loans held for investment, net	$ 18,600,723	$ 17,244,830

Allowance for Loan Losses - Acc

Allowance for Loan Losses - Accrued Interest Receivable (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Receivables [Abstract]
Total Interest Receivable	$ 1,045,577	$ 951,138
Greater Than 90 Days Past Due	1,783	1,372
Allowance for Uncollectible Interest	$ 4,694	$ 4,664

Deposits - Summary of Total Dep

Deposits - Summary of Total Deposits (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Banking and Thrift [Abstract]
Deposits - interest bearing	$ 16,497,006	$ 15,504,330
Deposits - non-interest bearing	1,640	1,053
Total deposits	$ 16,498,646	$ 15,505,383

Deposits - Additional Informati

Deposits - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Banking and Thrift [Abstract]
Deposits	$ 16,498,646		$ 15,505,383
Brokered deposits	8,600,000		8,200,000
Retail and other deposits	7,900,000		7,300,000
Stable interest-bearing deposits, total	5,800,000		5,500,000
Brokered deposit placement fee	2,800	$ 2,100
Third party broker fees paid	7,100	$ 2,100
Deposits exceeding FDIC insurance limits	404,500		395,500
Accrued interest on deposits	$ 36,800		$ 27,800

Deposits - Interest Bearing Dep

Deposits - Interest Bearing Deposits (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Amount
Money market	$ 8,107,996	$ 7,731,966
Savings	681,024	738,243
Certificates of deposit	7,707,986	7,034,121
Deposits - interest bearing	$ 16,497,006	$ 15,504,330
Weighted Average Stated Rate
Money market	2.01%	1.80%
Savings	1.40%	1.10%
Certificates of deposit	2.13%	1.93%

Borrowings - Company Borrowings

Borrowings - Company Borrowings (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Short Term	$ 0	$ 0
Long Term	3,744,345	3,275,270
Total	3,744,345	3,275,270
Unsecured borrowings
Debt Instrument [Line Items]
Short Term	0	0
Long Term	196,741	196,539
Total	196,741	196,539
Secured borrowings
Debt Instrument [Line Items]
Short Term	0	0
Long Term	3,547,604	3,078,731
Total	3,547,604	3,078,731
Secured borrowings | Private Education Loan securitization
Debt Instrument [Line Items]
Short Term	0	0
Long Term	3,547,604	3,078,731
Total	3,547,604	3,078,731
Secured borrowings | ABCP Facility
Debt Instrument [Line Items]
Short Term	0	0
Long Term	0	0
Total	$ 0	$ 0

Borrowings - Additional Informa

Borrowings - Additional Information (Details) - USD ($)	Mar. 21, 2018	Feb. 21, 2018	Mar. 31, 2018	Dec. 31, 2017	Apr. 05, 2017	Dec. 31, 2016
Line of Credit Facility [Line Items]
Short-term borrowings			$ 0	$ 0
Unsecured offering issued			$ 670,000,000	$ 1,448,000,000		$ 1,782,000,000
Estimated weighted average life of student loans (in years)			5 years 5 months 5 days	5 years 6 months 5 days
Uncommitted federal funds			$ 125,000,000
Lendable value of collateral			2,500,000,000	$ 2,600,000,000
ABCP borrowings | Commercial Paper
Line of Credit Facility [Line Items]
Private asset backed commercial paper education loan funding facility		$ 750,000,000
Ownership interest percentage in residual interest in ABCP facility		100.00%
Short-term borrowings			0
Private Education Loans
Line of Credit Facility [Line Items]
Total loan amount securitized at inception	$ 670,000,000
Amount of loan securitization sold to third parties	$ 670,000,000
Class A Notes
Line of Credit Facility [Line Items]
Ownership interest percentage	100.00%
Proceeds from loan securitization sold to third parties	$ 668,000,000
Class A and B Notes
Line of Credit Facility [Line Items]
Estimated weighted average life of student loans (in years)	4 years 5 months 5 days
Private Education Loans, 2016 Term A
Line of Credit Facility [Line Items]
Loans pledged as collateral			701,000,000
LIBOR | ABCP borrowings | Commercial Paper
Line of Credit Facility [Line Items]
Basis spread on variable rate		0.85%
LIBOR | Class A and B Notes
Line of Credit Facility [Line Items]
Basis spread on variable rate	0.78%
Minimum | ABCP borrowings | Commercial Paper
Line of Credit Facility [Line Items]
Financing cost percentage of unused borrowing capacity		0.35%
Maximum | ABCP borrowings | Commercial Paper
Line of Credit Facility [Line Items]
Financing cost percentage of unused borrowing capacity		0.45%
Unsecured borrowings
Line of Credit Facility [Line Items]
Short-term borrowings			0	$ 0
Unsecured borrowings | Senior Unsecured Notes Due April 5, 2022
Line of Credit Facility [Line Items]
Unsecured offering issued			$ 197,000,000		$ 200,000,000
Interest rate stated percentage					5.125%

Borrowings - Securitizations (D

Borrowings - Securitizations (Details) - USD ($)	Feb. 28, 2017	Oct. 31, 2016	Jul. 31, 2016	May 31, 2016	Mar. 31, 2018	Nov. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Securities Financing Transaction [Line Items]
Total Issued					$ 670,000,000		$ 1,448,000,000	$ 1,782,000,000
Total loan and accrued interest amount securitized at inception on-balance sheet term securitization					744,917,000		$ 1,606,804,000	$ 2,107,042,000
2016-A
Securities Financing Transaction [Line Items]
Total Issued				$ 501,000,000
Weighted Average Life (in years)				4 years 3 days
2016-B
Securities Financing Transaction [Line Items]
Total Issued			$ 607,000,000
Weighted Average Life (in years)			4 years 3 days
2016-C
Securities Financing Transaction [Line Items]
Total Issued		$ 674,000,000
Weighted Average Life (in years)		4 years 3 months 7 days
2017-A
Securities Financing Transaction [Line Items]
Total Issued	$ 772,000,000
Weighted Average Life (in years)	4 years 3 months 7 days
2017-B
Securities Financing Transaction [Line Items]
Total Issued						$ 676,000,000
Basis spread on variable rate						0.80%
Weighted Average Life (in years)						4 years 25 days
2018-A
Securities Financing Transaction [Line Items]
Total Issued					$ 670,000,000
Basis spread on variable rate					0.78%
Weighted Average Life (in years)					4 years 5 months 4 days
LIBOR | 2016-A
Securities Financing Transaction [Line Items]
Basis spread on variable rate				1.38%
LIBOR | 2016-B
Securities Financing Transaction [Line Items]
Basis spread on variable rate			1.36%
LIBOR | 2016-C
Securities Financing Transaction [Line Items]
Basis spread on variable rate		1.15%
LIBOR | 2017-A
Securities Financing Transaction [Line Items]
Basis spread on variable rate	0.93%

Borrowings - Financing VIEs (De

Borrowings - Financing VIEs (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Debt Outstanding
Short Term	$ 0	$ 0
Long Term	3,744,345	3,275,270
Total	3,744,345	3,275,270
Carrying Amount of Assets Securing Debt Outstanding
Restricted Cash	120,084	101,836
Other Assets	93,332	84,853
Variable Interest Entity, Primary Beneficiary
Debt Outstanding
Short Term	0	0
Long Term	3,547,604	3,078,731
Total	3,547,604	3,078,731
Carrying Amount of Assets Securing Debt Outstanding
Loans	4,243,820	3,691,024
Restricted Cash	115,009	96,983
Other Assets	290,530	240,369
Total	4,649,359	4,028,376
Variable Interest Entity, Primary Beneficiary | Private Education Loan securitization
Debt Outstanding
Short Term	0	0
Long Term	3,547,604	3,078,731
Total	3,547,604	3,078,731
Carrying Amount of Assets Securing Debt Outstanding
Loans	4,243,820	3,691,024
Restricted Cash	106,351	95,966
Other Assets	280,646	240,208
Total	4,630,817	4,027,198
Variable Interest Entity, Primary Beneficiary | ABCP Facility
Debt Outstanding
Short Term	0	0
Long Term	0	0
Total	0	0
Carrying Amount of Assets Securing Debt Outstanding
Loans	0	0
Restricted Cash	8,658	1,017
Other Assets	9,884	161
Total	$ 18,542	$ 1,178

Derivative Financial Instrume51

Derivative Financial Instruments - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Notional value	$ 6,400,000
Cash collateral pledged	0	$ 0
Net derivatives	31,300	19,600
Cash collateral held relative to derivative exposure		0
Cash collateral pledged	31,600	21,600
Chicago Mercantile Exchange
Derivative [Line Items]
Notional value	$ 5,700,000
Percent of total notional derivative contracts	89.80%
London Clearing House
Derivative [Line Items]
Notional value	$ 700,000
Percent of total notional derivative contracts	10.20%
Interest rate swaps
Derivative [Line Items]
Notional value	$ 6,405,020	5,459,075
Net position	(295)	(1,772)
Designated as Hedging Instrument | Fair Value Hedges | Interest rate swaps
Derivative [Line Items]
Notional value	3,867,204	3,062,849
Net position	$ 794	$ 630

Derivative Financial Instrume52

Derivative Financial Instruments - Impact of Derivatives on Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Derivative Assets	$ 794	$ 812
Interest rate swaps
Derivatives, Fair Value [Line Items]
Derivative Assets	794	812
Derivative Liabilities	(1,089)	(2,584)
Total net derivatives	(295)	(1,772)
Interest rate swaps | Derivatives Not Designated as Hedges
Derivatives, Fair Value [Line Items]
Derivative Assets	0	182
Derivative Liabilities	(36)	0
Total net derivatives	(36)	182
Interest rate swaps | Cash Flow | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative Assets	0	0
Derivative Liabilities	(1,053)	(2,584)
Total net derivatives	(1,053)	(2,584)
Interest rate swaps | Fair Value | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative Assets	794	630
Derivative Liabilities	0	0
Total net derivatives	$ 794	$ 630

Derivative Financial Instrume53

Derivative Financial Instruments - Offsetting Assets and Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Other Assets
Gross position	$ 794	$ 812
Impact of master netting agreement	(794)	(812)
Derivative values with impact of master netting agreements (as carried on balance sheet)	0	0
Cash collateral pledged	0	0
Net position	0	0
Other Liabilities
Cash collateral pledged	31,600	21,600
Other Liabilities
Other Liabilities
Gross position	(1,089)	(2,584)
Impact of master netting agreement	794	812
Derivative values with impact of master netting agreements (as carried on balance sheet)	(295)	(1,772)
Cash collateral pledged	31,637	21,586
Net position	$ 31,342	$ 19,814

Derivative Financial Instrume54

Derivative Financial Instruments - Notional Values (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Notional values	$ 6,400,000
Interest rate swaps
Derivatives, Fair Value [Line Items]
Notional values	6,405,020	$ 5,459,075
Interest rate swaps | Derivatives Not Designated as Hedges
Derivatives, Fair Value [Line Items]
Notional values	1,161,000	987,577
Interest rate swaps | Cash Flow Hedges | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Notional values	1,376,816	1,408,649
Interest rate swaps | Fair Value Hedges | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Notional values	3,867,204	3,062,849
Other
Derivatives, Fair Value [Line Items]
Notional values	5,476	3,245
Other | Derivatives Not Designated as Hedges
Derivatives, Fair Value [Line Items]
Notional values	5,476	3,245
Other | Cash Flow Hedges | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Notional values	0	0
Other | Fair Value Hedges | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Notional values	$ 0	$ 0

Derivative Financial Instrume55

Derivative Financial Instruments - Impact of Derivatives on Consolidated Statements of Income (Details) - Interest rate swaps - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Trading
Gain (loss) on derivatives, net	$ 1,816	$ (4,170)
Designated as Hedging Instrument | Fair Value Hedges
Fair Value Hedges
Hedge ineffectiveness gains (losses) recorded in earnings	5,853	(4,167)
Realized gains (losses) recorded in interest expense	(514)	4,547
Trading
Gain (loss) on derivatives, net	5,339	380
Designated as Hedging Instrument | Cash Flow Hedges
Cash Flow Hedges
Hedge ineffectiveness losses recorded in earnings	2,684	(72)
Realized losses recorded in interest expense	(1,562)	(3,339)
Trading
Gain (loss) on derivatives, net	1,122	(3,411)
Trading
Trading
Interest reclassification	110	80
Realized losses recorded in earnings	(4,755)	(1,219)
Gain (loss) on derivatives, net	$ (4,645)	$ (1,139)

Derivative Financial Instrume56

Derivative Financial Instruments - Impact of Derivatives on Consolidated Statement of Changes in Stockholders' Equity (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Amount of gain recognized in other comprehensive income (loss)	$ 18,728	$ 1,440
Less: amount of (loss) gain reclassified in interest expense	(1,562)	(3,339)
Total change in other comprehensive income (loss) for unrealized gains on derivatives, before income tax (expense) benefit	$ 20,290	$ 4,779

Stockholders' Equity - Additio

Stockholders' Equity - Additional Detail (Details)	Mar. 31, 2018$ / shares
Common Stock
Class of Stock [Line Items]
Common stock closing price (in dollars per share)	$ 11.21

Stockholders' Equity - Common s

Stockholders' Equity - Common stock repurchased (Details) - $ / shares	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Equity [Abstract]
Shares repurchased related to employee stock-based compensation plans (in shares)	2,740,018	1,603,487
Average purchase price per share (in dollars per share)	$ 11.31	$ 11.96
Common shares issued (in shares)	5,559,991	3,738,717

Earnings per Common Share (Deta

Earnings per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Numerator:
Net income	$ 126,254	$ 94,943
Preferred stock dividends	3,397	5,575
Net income attributable to SLM Corporation common stock	$ 122,857	$ 89,368
Denominator:
Weighted average shares used to compute basic EPS (in shares)	433,952,000	429,891,000
Effect of dilutive securities:
Dilutive effect of stock options, restricted stock and restricted stock units and Employee Stock Purchase Plan (ESPP) (in shares)	5,025,000	8,844,000
Weighted average shares used to compute diluted EPS (in shares)	438,977,000	438,735,000
Basic earnings per common share attributable to SLM Corporation (in dollars per share)	$ 0.28	$ 0.21
Diluted earnings per common share attributable to SLM Corporation (in dollars per share)	$ 0.28	$ 0.20
Securities excluded from computation of EPS (in shares)	0	0

Fair Value Measurements - Valua

Fair Value Measurements - Valuation of Financial Instruments that are Marked-to-Market on Recurring Basis (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Assets
Available-for-sale investments	$ 229,114	$ 244,088
Derivative instruments	0	0
Fair Value Measurements on a Recurring Basis
Assets
Available-for-sale investments	229,114	244,088
Derivative instruments	794	812
Total earning assets	229,908	244,900
Liabilities
Derivative instruments	(1,089)	(2,584)
Fair Value Measurements on a Recurring Basis | Level 1
Assets
Available-for-sale investments	0	0
Derivative instruments	0	0
Total earning assets	0	0
Liabilities
Derivative instruments	0	0
Fair Value Measurements on a Recurring Basis | Level 2
Assets
Available-for-sale investments	229,114	244,088
Derivative instruments	794	812
Total earning assets	229,908	244,900
Liabilities
Derivative instruments	(1,089)	(2,584)
Fair Value Measurements on a Recurring Basis | Level 3
Assets
Available-for-sale investments	0	0
Derivative instruments	0	0
Total earning assets	0	0
Liabilities
Derivative instruments	$ 0	$ 0

Fair Value Measurements - Fair

Fair Value Measurements - Fair Values of Financial Assets and Liabilities, Including Derivative Financial Instruments (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Earning assets
Loans held for investment, net, difference	$ 2,097,587	$ 2,105,495
Cash and cash equivalents, difference	0	0
Tax indemnification receivable	169,242	168,011
Derivative instruments	0	0
Total earning assets, difference	2,097,587	2,105,495
Interest-bearing liabilities
Long-term borrowings, difference	12,649	(24,601)
Total interest-bearing liabilities, difference	(375,315)	(34,688)
Excess of net asset fair value over carrying value	1,722,272	2,070,807
Certificates of deposit
Interest-bearing liabilities
Certificates of deposit, difference	(387,964)	(10,087)
Fair Value
Earning assets
Loans held for investment, net	22,264,191	20,673,136
Cash and cash equivalents	1,435,649	1,534,339
Available-for-sale investments	229,114	244,088
Accrued interest receivable	1,063,449	967,482
Tax indemnification receivable	169,242	168,011
Derivative instruments	794	812
Total earning assets	25,162,439	23,587,868
Interest-bearing liabilities
Long-term borrowings	3,731,696	3,299,871
Accrued interest payable	46,396	35,363
Derivative instruments	1,089	2,584
Total interest-bearing liabilities	20,664,151	18,852,235
Fair Value | Money-market and savings accounts
Interest-bearing liabilities
Deposits	8,789,020	8,470,209
Fair Value | Certificates of deposit
Interest-bearing liabilities
Deposits	8,095,950	7,044,208
Carrying Value
Earning assets
Loans held for investment, net	20,166,604	18,567,641
Cash and cash equivalents	1,435,649	1,534,339
Available-for-sale investments	229,114	244,088
Accrued interest receivable	1,063,449	967,482
Tax indemnification receivable	169,242	168,011
Derivative instruments	794	812
Total earning assets	23,064,852	21,482,373
Interest-bearing liabilities
Long-term borrowings	3,744,345	3,275,270
Accrued interest payable	46,396	35,363
Derivative instruments	1,089	2,584
Total interest-bearing liabilities	20,288,836	18,817,547
Carrying Value | Money-market and savings accounts
Interest-bearing liabilities
Deposits	8,789,020	8,470,209
Carrying Value | Certificates of deposit
Interest-bearing liabilities
Deposits	$ 7,707,986	$ 7,034,121

Arrangements with Navient Cor62

Arrangements with Navient Corporation (Details) - USD ($) $ in Millions	Mar. 31, 2018	Apr. 30, 2014
Related Party Transactions [Abstract]
Deferred taxes to be indemnified		$ 283
Amount remaining	$ 35
Remaining balance of indemnification receivable in connection with the spin-off	27
Liability for uncertainty in income taxes	25
Liability for uncertainty in income taxes relating to historical transactions	$ 109

Regulatory Capital - Well Capit

Regulatory Capital - Well Capitalized Regulatory Requirements (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Actual Amount
Common Equity Tier I Capital (to Risk-Weighted Assets)	$ 2,494,964	$ 2,350,081
Tier 1 Capital (to Risk-Weighted Assets)	2,494,964	2,350,081
Total Capital (to Risk-Weighted Assets)	2,761,446	2,597,926
Tier 1 Capital (to Average Assets)	$ 2,494,964	$ 2,350,081
Actual Ratio
Common Equity Tier I Capital (to Risk-Weighted Assets)	11.70%	11.90%
Tier 1 Capital (to Risk-Weighted Assets)	11.70%	11.90%
Total Capital (to Risk-Weighted Assets)	13.00%	13.10%
Tier 1 Capital (to Average Assets)	11.00%	11.00%
Well Capitalized Regulatory Requirements, Amount
Common Equity Tier I Capital (to Risk-Weighted Assets)	$ 1,385,322	$ 1,288,435
Tier 1 Capital (to Risk-Weighted Assets)	1,705,011	1,585,767
Total Capital (to Risk-Weighted Assets)	2,131,264	1,982,208
Tier 1 Capital (to Average Assets)	$ 1,138,524	$ 1,067,739
Well Capitalized Regulatory Requirements, Ratio
Common Equity Tier I Capital (to Risk-Weighted Assets)	6.50%	6.50%
Tier 1 Capital (to Risk-Weighted Assets)	8.00%	8.00%
Total Capital (to Risk-Weighted Assets)	10.00%	10.00%
Tier 1 Capital (to Average Assets)	5.00%	5.00%

Regulatory Capital - Additional

Regulatory Capital - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Banking and Thrift [Abstract]
Dividends	$ 0	$ 0

Commitments, Contingencies an65

Commitments, Contingencies and Guarantees - Additional Information (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2018USD ($)
Commitments and Contingencies Disclosure [Abstract]
Contractual obligation	$ 500
Other liabilities reserve	$ 0.3
Loss contingency, loss emergence period	1 year

Uncategorized Items - slm-20180

Label	Element	Value
Restricted Cash and Cash Equivalents	us-gaap_RestrictedCashAndCashEquivalents	$ 94,146,000
Restricted Cash and Cash Equivalents	us-gaap_RestrictedCashAndCashEquivalents	$ 120,084,000