Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Interest income:
Loan interest	$ 757,731	$ 751,280	$ 726,258
Investment interest	12,695	9,466	7,851
Total interest income	770,426	760,746	734,109
Interest expense:
Interest on bonds and notes payable	465,188	388,183	302,210
Net interest income	305,238	372,563	431,899
Less provision for loan losses	14,450	13,500	10,150
Net interest income after provision for loan losses	290,788	359,063	421,749
Other income:
Loan systems and servicing revenue	223,000	214,846	239,858
Tuition payment processing, school information, and campus commerce revenue	145,751	132,730	120,365
Communications revenue	25,700	17,659	0
Enrollment services revenue	0	4,326	51,073
Other income	52,826	53,929	47,262
Gain on sale of loans and debt repurchases, net	2,902	7,981	5,153
Derivative market value and foreign currency transaction adjustments and derivative settlements, net	(18,554)	49,795	4,401
Total other income	431,625	481,266	468,112
Operating expenses:
Salaries and benefits	301,885	255,924	247,914
Depreciation and amortization	39,541	33,933	26,343
Loan servicing fees	22,734	25,750	30,213
Cost to provide communications services	9,950	6,866	0
Cost to provide enrollment services	0	3,623	41,733
Other expenses	121,619	115,419	123,014
Total operating expenses	495,729	441,515	469,217
Income before income taxes	226,684	398,814	420,644
Income tax expense	64,863	141,313	152,380
Net income	161,821	257,501	268,264
Net loss (income) attributable to noncontrolling interests	11,345	(750)	(285)
Net income attributable to Nelnet, Inc.	$ 173,166	$ 256,751	$ 267,979
Earnings per common share:
Net income attributable to Nelnet, Inc. shareholders - basic and diluted (in dollars per share)	$ 4.14	$ 6.02	$ 5.89
Weighted average common shares outstanding - basic and diluted (in shares)	41,791,941	42,669,070	45,529,340