Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income (loss)	$ 170,126	$ 122,063	$ 72,120
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization and depreciation	38,589	31,146	31,152
Adjustment to loss on sale of business	0	0	(40,815)
Gain on sale of discontinued operation	0	(114,834)	0
Share-based compensation expense	29,930	28,893	27,602
Deferred income taxes	8,645	8,924	7,771
Excess tax benefit on share-based compensation	(620)	(6,089)	(1,349)
Net realized gain on investments	(24,061)	(36,680)	(33,029)
Other changes	31,539	15,158	22,542
Changes in assets and liabilities, net of effects of acquisitions and dispositions:
Premiums receivable and unearned premiums	(83,822)	(212,998)	65,221
Other current assets, receivables and noncurrent assets	1,425	(28,374)	(54,031)
Amounts receivable/payable under government contracts	20,896	(8,989)	32,754
Reserves for claims and other settlements	(53,898)	164,306	(29,898)
Accounts payable and other liabilities	(42,910)	70,014	3,340
Net cash provided by operating activities	95,839	32,540	103,380
CASH FLOWS FROM INVESTING ACTIVITIES:
Sales of investments	696,534	1,350,003	1,760,336
Maturities of investments	93,225	135,394	189,137
Purchases of investments	(722,223)	(1,678,582)	(1,814,431)
Sales of property and equipment	0	24	0
Purchases of property and equipment	(59,525)	(73,101)	(64,260)
Net cash received from sale of business	0	248,238	0
Purchase price adjustment on sale of Northeast Health Plans	0	0	162,101
Sales (purchases) of restricted investments and other	(7,432)	5,466	(10,656)
Net cash provided by (used in) investing activities	579	(12,558)	222,227
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from exercise of stock options and employee stock purchases	10,762	16,941	13,356
Excess tax benefit on share-based compensation	620	6,089	1,349
Repurchases of common stock	(77,810)	(69,496)	(389,850)
Borrowings under financing arrangements	345,000	110,000	978,500
Repayment of borrowings under financing arrangements	(345,000)	(122,500)	(872,212)
Net (decrease) increase in checks outstanding, net of deposits	(23,842)	23,842	(46,718)
Customer funds administered	86,897	124,999	(129,917)
Net cash (used in) provided by financing activities	(3,373)	89,875	(445,492)
Net increase (decrease) in cash and cash equivalents	93,045	109,857	(119,885)
Cash and cash equivalents, beginning of year	340,110	230,253	350,138
Cash and cash equivalents, end of year	433,155	340,110	230,253
SUPPLEMENTAL CASH FLOWS DISCLOSURE:
Interest paid	30,789	31,134	31,332
Income taxes paid	80,119	5,001	55,882
SUPPLEMENTAL SCHEDULE OF NON-CASH INVESTING AND FINANCING ACTIVITIES:
Accretion of deferred revenues into earnings	0	12,000	2,738
Amortization of discounts into earnings	$ 0	$ 0	$ 10,429