Consolidated Statements of Operations and Comprehensive Income (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Operating revenues:
Managed care premiums	$ 12,926,375	$ 11,014,950	$ 10,414,640
Management services	1,186,988	1,171,733	1,173,276
Total operating revenues	14,113,363	12,186,683	11,587,916
Operating expenses:
Medical costs	10,853,774	9,041,402	8,265,947
Cost of sales	266,803	283,544	252,052
Selling, general and administrative	2,080,236	2,016,042	1,961,947
Provider class action - (release) / charge	0	(159,300)	278,000
Depreciation and amortization	152,859	136,865	140,685
Total operating expenses	13,353,672	11,318,553	10,898,631
Operating earnings	759,691	868,130	689,285
Interest expense	99,468	99,062	80,418
Other income, net	124,312	89,033	77,667
Earnings before income taxes	784,535	858,101	686,534
Provision for income taxes	297,472	314,996	247,918
Net earnings	487,063	543,105	438,616
Net earnings per common share:
Basic earnings per common share (in dollars per share)	$ 3.54	$ 3.70	$ 2.96
Diluted earnings per common share (in dollars per share)	$ 3.52	$ 3.67	$ 2.94
Cash dividends declared per common share	$ 0.5	$ 0	$ 0
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Unrealized investment holding gains	54,626	48,274	10,501
Reclassification adjustment, net	(40,355)	(17,046)	(11,034)
Income tax (provision) benefit	(5,520)	(11,840)	208
Other comprehensive Income (loss), net of tax	8,751	19,388	(325)
Comprehensive income	$ 495,814	$ 562,493	$ 438,291