Segment Information (Premium Revenue By Line Of Business) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Segment Reporting Information [Line Items]
Health plans services premiums	$ 2,578,874	$ 2,618,927	$ 5,210,943	$ 5,239,876
Commercial Premium Revenue [Member]
Segment Reporting Information [Line Items]
Health plans services premiums	1,298,600	1,436,500	2,624,000	2,889,700
Medicare Premium Revenue [Member]
Segment Reporting Information [Line Items]
Health plans services premiums	688,600	691,400	1,395,000	1,406,500
Medicaid Premium Revenue [Member]
Segment Reporting Information [Line Items]
Health plans services premiums	$ 591,700	$ 491,000	$ 1,191,900	$ 943,700