Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands	6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010
Operating activities:
Net income	$ 34,828	$ 21,169
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	34,602	23,912
Deferred income taxes	(2,839)	624
Stock-based compensation	8,374	4,508
Non-cash interest on convertible senior notes	2,711	2,509
Amortization of premium/discount on investments	3,439	560
Amortization of deferred financing costs	1,007	687
Unrealized gain on trading securities		(2,860)
Loss on rights agreement		2,611
Tax deficiency from employee stock compensation	(489)	(383)
Changes in operating assets and liabilities:
Receivables	(4,424)	(1,598)
Prepaid expenses and other current assets	(2,780)	(6,348)
Medical claims and benefits payable	(12,743)	30,284
Accounts payable and accrued liabilities	(8,715)	27,958
Deferred revenue	69,498	(82,680)
Income taxes	(7,571)	4,910
Net cash provided by operating activities	114,898	25,863
Investing activities:
Purchases of equipment	(30,866)	(17,523)
Purchases of investments	(183,647)	(91,768)
Sales and maturities of investments	121,434	116,276
Net cash paid in business combinations	(3,253)	(134,400)
Increase in deferred contract costs	(16,405)	(8,018)
Increase in restricted investments	(8,230)	(4,754)
Change in other noncurrent assets and liabilities	2,190	757
Net cash used in investing activities	(118,777)	(139,430)
Financing activities:
Amount borrowed under credit facility		105,000
Credit facility fees paid		(1,671)
Proceeds from employee stock plans	5,640	1,543
Excess tax benefits from employee stock compensation	1,566	179
Net cash provided by financing activities	7,206	105,051
Net increase (decrease) in cash and cash equivalents	3,327	(8,516)
Cash and cash equivalents at beginning of period	455,886	469,501
Cash and cash equivalents at end of period	459,213	460,985
Supplemental cash flow information:
Income taxes	30,863	6,604
Interest	4,385	6,222
Schedule of non-cash investing and financing activities:
Retirement of common stock used for stock-based compensation	3,714	1,673
Details of business combinations:
Increase in fair value of assets acquired	(256)	(143,983)
(Decrease) increase in fair value of liabilities assumed	(1,045)	11,832
Decrease in payable to seller	(1,952)	(2,249)
Net cash paid in business combinations	$ (3,253)	$ (134,400)