Segment Information (Premium Revenue By Line Of Business) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Segment Reporting Information [Line Items]
Health plans services premiums	$ 3,261,878	$ 2,578,874	$ 6,143,223	$ 5,210,943
Commercial Premium Revenue [Member]
Segment Reporting Information [Line Items]
Health plans services premiums	1,377,500	1,298,600	2,641,600	2,624,000
Medicare Premium Revenue [Member]
Segment Reporting Information [Line Items]
Health plans services premiums	757,200	688,600	1,512,400	1,395,000
Medicaid Premium Revenue [Member]
Segment Reporting Information [Line Items]
Health plans services premiums	1,121,900	591,700	1,983,900	1,191,900
Dual eligibles premium revenue [Member]
Segment Reporting Information [Line Items]
Health plans services premiums	$ 5,300	$ 0	$ 5,300	$ 0