Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Current assets:
Cash and cash equivalents	$ 546,811	$ 763,946
Short-term investments	394,346	230,007
Premium receivables	106,510	83,203
Deferred income taxes	24,720	28,063
Provider and other receivables	34,767	32,861
Prepaid expenses	37,851	13,538
Other current assets	20,755	7,083
Total current assets	1,165,760	1,158,701
Long-term investments	1,118,127	639,165
Investments on deposit for licensure	128,063	114,839
Property, equipment and software, net	110,602	96,967
Other long-term assets	18,300	13,220
Goodwill	260,496	260,496
Total assets	2,801,348	2,283,388
Current liabilities:
Claims payable	573,448	510,675
Unearned revenue	780	103,067
Accrued payroll and related liabilities	63,475	71,253
Contractual refunds payable	40,123	44,563
Accounts payable, accrued expenses and other	149,353	121,283
Current portion of long-term debt	256,995	0
Total current liabilities	1,084,174	850,841
Long-term debt	400,000	245,750
Deferred income taxes	19,447	7,393
Other long-term liabilities	13,208	13,767
Total liabilities	1,516,829	1,117,751
Commitments and contingencies (Note 10)
Stockholders' equity:
Common stock, $0.01 par value. Authorized 100,000,000 shares; outstanding 46,878,474 and 48,167,229 at December 31, 2011 and 2010, respectively	573	554
Additional paid-in capital	637,605	543,611
Accumulated other comprehensive income	11,942	627
Retained earnings	1,059,624	864,003
Stockholders' equity before treasury stock	1,709,744	1,408,795
Less treasury stock at cost (11,201,634 and 7,759,234 shares at December 31, 2011 and 2010, respectively)	(425,225)	(243,158)
Total stockholders' equity	1,284,519	1,165,637
Total liabilities and stockholders' equity	$ 2,801,348	$ 2,283,388