Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue:
Premium revenue	$ 16,208	$ 17,612	$ 18,854
Premium tax revenue	489	417	438
Health insurer fees reimbursed	0	329	0
Service revenue	0	407	521
Investment income and other revenue	132	125	70
Total revenue	16,829	18,890	19,883
Operating expenses:
General and administrative expenses	1,296	1,333	1,594
Premium tax expenses	489	417	438
Health insurer fees	0	348	0
Depreciation and amortization	89	99	137
Restructuring costs	6	46	234
Impairment losses	0	0	470
Total operating expenses	15,785	17,744	20,438
Loss on sales of subsidiaries, net of gain	0	(15)	0
Operating income (loss)	1,044	1,131	(555)
Other expenses, net:
Interest expense	87	115	118
Other (income) expenses, net	(15)	17	(61)
Total other expenses, net	72	132	57
Income (loss) before income tax expense (benefit)	972	999	(612)
Income tax expense (benefit)	235	292	(100)
Net income (loss)	$ 737	$ 707	$ (512)
Net income (loss) per share:
Basic (in dollars per share)	$ 11.85	$ 11.57	$ (9.07)
Diluted (in dollars per share)	$ 11.47	$ 10.61	$ (9.07)
Weighted average shares outstanding:
Basic (in shares)	62.2	61.1	56.4
Diluted (in shares)	64.2	66.6	56.4
Medical care costs
Operating expenses:
Cost of revenue	$ 13,905	$ 15,137	$ 17,073
Cost of service revenue
Operating expenses:
Cost of revenue	$ 0	$ 364	$ 492