CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Interest income:
Loans	$ 1,894,687	$ 1,413,505	$ 1,060,487
Investments	6,162	8,288	9,160
Cash and cash equivalents	34,503	15,510	7,599
Total interest income	1,935,352	1,437,303	1,077,246
Interest expense:
Deposits	389,349	223,691	148,408
Interest expense on short-term borrowings	5,833	6,341	7,322
Interest expense on long-term borrowings	127,106	78,050	30,178
Total interest expense	522,288	308,082	185,908
Net interest income	1,413,064	1,129,221	891,338
Less: provisions for credit losses	244,864	185,765	159,405
Net interest income after provisions for credit losses	1,168,200	943,456	731,933
Non-interest (loss) income:
Gains on sales of loans, net	2,060	0	230
Losses on sales of securities, net	(1,549)	0	0
Losses on derivatives and hedging activities, net	(87)	(8,266)	(958)
Other (loss) income	(52,319)	5,364	69,544
Total non-interest (loss) income	(51,895)	(2,902)	68,816
Non-interest expenses:
Compensation and benefits	252,346	213,319	183,996
FDIC assessment fees	32,786	28,950	19,209
Other operating expenses	271,844	206,820	183,108
Total non-interest expenses	556,976	449,089	386,313
Income before income tax expense	559,329	491,465	414,436
Income tax expense	71,853	202,531	164,109
Net income	487,476	288,934	250,327
Preferred stock dividends	15,640	15,714	21,204
Net income attributable to SLM Corporation common stock	$ 471,836	$ 273,220	$ 229,123
Basic earnings per common share attributable to SLM Corporation	$ 1.08	$ 0.63	$ 0.54
Average common shares outstanding	435,054	431,216	427,876
Diluted earnings per common share attributable to SLM Corporation	$ 1.07	$ 0.62	$ 0.53
Average common and common equivalent shares outstanding	439,681	438,551	432,919