Segment Information (Premium Revenue By Line Of Business) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Segment Reporting Information [Line Items]
Health plans services premiums	$ 2,606,754	$ 2,578,689	$ 7,817,697	$ 7,818,565
Commercial Premium Revenue [Member]
Segment Reporting Information [Line Items]
Health plans services premiums	1,279,800	1,420,400	3,903,800	4,310,000
Medicare Premium Revenue [Member]
Segment Reporting Information [Line Items]
Health plans services premiums	685,400	682,900	2,080,300	2,089,400
Medicaid Premium Revenue [Member]
Segment Reporting Information [Line Items]
Health plans services premiums	$ 641,600	$ 475,400	$ 1,833,600	$ 1,419,200