Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010
Operating activities:
Net income	$ 53,778	$ 37,342
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	52,414	40,485
Deferred income taxes	8,069	4,463
Stock-based compensation	12,723	7,268
Non-cash interest on convertible senior notes	4,095	3,800
Amortization of premium/discount on investments	5,300	1,023
Amortization of deferred financing costs	2,451	1,278
Unrealized gain on trading securities		(4,170)
Loss on rights agreement		3,807
Tax deficiency from employee stock compensation	(647)	(676)
Changes in operating assets and liabilities:
Receivables	(11,789)	(64,896)
Prepaid expenses and other current assets	(1,819)	(7,707)
Medical claims and benefits payable	6,699	33,347
Accounts payable and accrued liabilities	246	15,131
Deferred revenue	42,600	(64,337)
Income taxes	(18,957)	3,327
Net cash provided by operating activities	155,163	9,485
Investing activities:
Purchases of equipment	(45,921)	(31,918)
Purchases of investments	(258,209)	(162,620)
Sales and maturities of investments	226,413	184,170
Net cash paid in business combinations	(3,253)	(127,231)
Increase in deferred contract costs	(32,765)	(20,616)
Increase in restricted investments	(8,394)	(8,513)
Change in other noncurrent assets and liabilities	(533)	2,340
Net cash used in investing activities	(122,662)	(164,388)
Financing activities:
Amount borrowed under credit facility		105,000
Proceeds from common stock offering, net of issuance costs		111,246
Repayment of amount borrowed under credit facility		(105,000)
Treasury stock purchases	(7,000)
Credit facility fees paid	(1,125)	(1,671)
Proceeds from employee stock plans	5,640	1,862
Excess tax benefits from employee stock compensation	1,590	420
Net cash (used in) provided by financing activities	(895)	111,857
Net increase (decrease) in cash and cash equivalents	31,606	(43,046)
Cash and cash equivalents at beginning of period	455,886	469,501
Cash and cash equivalents at end of period	487,492	426,455
Supplemental cash flow information:
Income taxes	43,550	12,129
Interest	5,026	7,175
Schedule of non-cash investing and financing activities:
Common stock used for stock-based compensation	3,751	2,173
Details of business combinations:
Increase in fair value of assets acquired	(256)	(161,862)
(Decrease) increase in fair value of liabilities assumed	(1,045)	25,880
(Decrease) increase in payable to seller	(1,952)	8,751
Net cash paid in business combinations	$ (3,253)	$ (127,231)