Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income (loss)	$ 83,533	$ 98,024
Adjustments to reconcile net income to net cash (used in) provided by operating activities:
Amortization and depreciation	18,953	14,815
Share-based compensation expense	16,877	18,067
Gain on sale of discontinued operation	0	119,440
Deferred income taxes	12,748	9,453
Excess tax benefit on share-based compensation	(430)	(6,059)
Net realized (gain) loss on investments	(22,936)	(25,389)
Other changes	15,524	7,047
Changes in assets and liabilities, net of effects of acquisitions and dispositions:
Premiums receivable and unearned premiums	(232,780)	27,172
Other current assets, receivables and noncurrent assets	27,481	(52,356)
Amounts receivable/payable under government contracts	29,051	(20,754)
Reserves for claims and other settlements	(24,887)	136,826
Accounts payable and other liabilities	(57,604)	36,527
Net cash (used in) provided by operating activities	(134,470)	123,933
CASH FLOWS FROM INVESTING ACTIVITIES:
Sales of investments	573,406	1,015,252
Maturities of investments	51,414	69,100
Purchases of investments	(559,442)	(1,010,613)
Purchases of property and equipment	(26,765)	(37,660)
Net cash received from sale of business	0	248,238
(Purchases) sales of restricted investments and other	(2,589)	6,895
Net cash provided by investing activities	36,024	291,212
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from exercise of stock options and employee stock purchases	8,173	16,589
Excess tax benefit on share-based compensation	430	6,059
Repurchases of common stock	(77,464)	(28,794)
Borrowings under financing arrangements	323,000	100,000
Repayment of borrowings under financing arrangements	(298,000)	(122,500)
Net increase (decrease) in checks outstanding, net of deposits	75,552	0
Customer funds administered	6,263	16,392
Net cash provided by (used in) financing activities	37,954	(12,254)
Net (decrease) increase in cash and cash equivalents	(60,492)	402,891
Cash and cash equivalents, beginning of period	340,110	230,253
Cash and cash equivalents, end of period	279,618	633,144
SUPPLEMENTAL CASH FLOWS DISCLOSURE:
Interest paid	15,499	15,626
Income taxes paid	$ 34,006	$ 2,431