CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement of Comprehensive Income [Abstract]
Net income	$ 274,284	$ 193,785	$ 257,593
Unrealized gains (losses) on investments:
Unrealized (losses) gains on investments	(2,205)	6,066	35,802
Reclassification adjustments for (gain) on sale of available-for-sale securities included in other income	0	0	(63,813)
Total unrealized (losses) gains on investments	(2,205)	6,066	(28,011)
Unrealized losses on cash flow hedges	(5,224)	(19,772)	0
Total unrealized (losses) gains	(7,429)	(13,706)	(28,011)
Income tax benefit	2,763	5,337	10,639
Other comprehensive loss, net of tax benefit	(4,666)	(8,369)	(17,372)
Comprehensive income	269,618	185,416	240,221
Less: comprehensive loss attributable to noncontrolling interest	0	(434)	(1,352)
Total comprehensive income attributable to SLM Corporation	$ 269,618	$ 185,850	$ 241,573