Segment Information (Premium Revenue By Line Of Business) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Segment Reporting Information [Line Items]
Health plans services premiums	$ 2,578,689	$ 2,487,767	$ 7,818,565	$ 7,379,951
Western Region Operations [Member]
Segment Reporting Information [Line Items]
Health plans services premiums	2,578,700	2,487,800	7,818,600	7,377,700
Commercial Premium Revenue [Member]
Segment Reporting Information [Line Items]
Health plans services premiums	1,420,400	1,494,800	4,310,000	4,466,000
Medicare Premium Revenue [Member]
Segment Reporting Information [Line Items]
Health plans services premiums	682,900	605,300	2,089,400	1,844,800
Medicaid Premium Revenue [Member]
Segment Reporting Information [Line Items]
Health plans services premiums	475,400	387,700	1,419,200	1,066,900
Divested Operations and Services [Member]
Segment Reporting Information [Line Items]
Health plans services premiums	$ 0	$ 0	$ 0	$ 2,300