Segment Information (Premium Revenue By Line Of Business) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Segment Reporting Information [Line Items]
Health plans services premiums	$ 3,977,891	$ 3,631,617	$ 11,702,123	$ 9,774,840
Commercial Premium Revenue [Member]
Segment Reporting Information [Line Items]
Health plans services premiums	1,412,300	1,430,800	4,158,200	4,072,400
Medicare Premium Revenue [Member]
Segment Reporting Information [Line Items]
Health plans services premiums	778,200	763,300	2,329,500	2,275,700
Medicaid Premium Revenue [Member]
Segment Reporting Information [Line Items]
Health plans services premiums	1,668,100	1,397,700	4,812,500	3,381,600
Dual eligibles premium revenue [Member]
Segment Reporting Information [Line Items]
Health plans services premiums	$ 119,300	$ 39,800	$ 401,900	$ 45,100