Segment Information (Premium Revenue By Line Of Business) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Segment Reporting Information [Line Items]
Health plans services premiums	$ 4,003,432	$ 3,261,878	$ 7,724,232	$ 6,143,223
Commercial Premium Revenue [Member]
Segment Reporting Information [Line Items]
Health plans services premiums	1,412,900	1,377,500	2,745,900	2,641,600
Medicare Premium Revenue [Member]
Segment Reporting Information [Line Items]
Health plans services premiums	782,400	757,200	1,551,300	1,512,400
Medicaid Premium Revenue [Member]
Segment Reporting Information [Line Items]
Health plans services premiums	1,673,100	1,121,900	3,144,400	1,983,900
Dual eligibles premium revenue [Member]
Segment Reporting Information [Line Items]
Health plans services premiums	$ 135,000	$ 5,300	$ 282,600	$ 5,300