Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 1,531,678	$ 1,399,162
Short-term investments	120,745	121,742
Accounts receivable, net	260,809	272,077
Other receivables, net	945,218	892,815
Other current assets	195,479	196,323
Total current assets	3,053,929	2,882,119
Long-term investments	2,713,291	2,658,582
Property and equipment, net	261,668	266,818
Goodwill	2,591,488	2,591,488
Other intangible assets, net	302,118	318,592
Other long-term assets	32,783	33,389
Total assets	8,955,277	8,750,988
Current liabilities:
Medical liabilities	1,476,557	1,418,914
Accounts payable and other accrued liabilities	509,930	488,175
Deferred revenue	150,999	137,981
Total current liabilities	2,137,486	2,045,070
Long-term debt	1,585,312	1,585,190
Other long-term liabilities	396,476	397,813
Total liabilities	4,119,274	4,028,073
Stockholders' equity:
Common stock, $.01 par value; 570,000 authorized 197,196 issued and 134,688 outstanding in 2013; 197,080 issued and 134,573 outstanding in 2012	1,972	1,971
Treasury stock, at cost; 62,508 in 2013; 62,507 in 2012	(1,920,996)	(1,920,749)
Additional paid-in capital	1,981,156	1,970,877
Accumulated other comprehensive income, net	53,757	69,220
Retained earnings	4,720,114	4,601,596
Total stockholders' equity	4,836,003	4,722,915
Total liabilities and stockholders' equity	$ 8,955,277	$ 8,750,988