Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues
Health plan services premiums	$ 15,553,348	$ 13,361,170	$ 10,377,073
Government contracts	628,451	603,975	572,266
Net investment income	55,494	45,166	69,613
Administrative services fees and other income	6,294	(1,725)	34,791
Total revenues	16,243,587	14,008,586	11,053,743
Expenses
Health plan services (excluding depreciation and amortization)	13,041,036	11,307,751	8,886,547
Government contracts	603,841	536,643	502,918
General and administrative	1,816,166	1,552,364	1,083,694
Selling	270,174	262,338	239,428
Depreciation and amortization	22,533	29,786	38,589
Interest	33,309	31,376	32,614
Asset impairment	1,884	88,536	0
Total expenses	15,788,943	13,808,794	10,783,790
Income from operations before income taxes	454,644	199,792	269,953
Income tax provision	268,967	54,163	99,827
Net income	$ 185,677	$ 145,629	$ 170,126
Net income per share:
Net income per share—basic (usd per share)	$ 2.40	$ 1.83	$ 2.14
Net income per share—diluted:
Net income per share—diluted (usd per share)	$ 2.37	$ 1.80	$ 2.12
Weighted average shares outstanding:
Basic (shares)	77,212	79,602	79,455
Diluted (shares)	78,358	80,777	80,404