Consolidated Statements of Income (Unaudited) (USD $) In Thousands, except Per Share data	3 Months Ended				9 Months Ended
	Sep. 30, 2011		Sep. 30, 2010		Sep. 30, 2011		Sep. 30, 2010
Revenue:
Premium revenue	$ 1,138,230		$ 1,005,115		$ 3,348,438		$ 2,947,020
Service revenue	37,728		32,271		111,290		53,325
Investment income	764		1,760		3,804		4,880
Total revenue	1,176,722		1,039,146		3,463,532		3,005,225
Expenses:
Medical care costs	959,158		845,937		2,822,049		2,508,366
Cost of service revenue	34,584		27,605		105,020		41,859
General and administrative expenses	99,610		88,660		290,967		245,619
Premium tax expenses	36,374		35,037		110,633		104,578
Depreciation and amortization	13,430		11,954		38,587		33,234
Total expenses	1,143,156		1,009,193		3,367,256		2,933,656
Operating income	33,566		29,953		96,276		71,569
Interest expense	4,380		4,600		11,666		12,056
Income before income taxes	29,186		25,353		84,610		59,513
Provision for income taxes	10,236		9,180		30,832		22,171
Net income	$ 18,950		$ 16,173		$ 53,778		$ 37,342
Net income per share (1):
Basic	$ 0.41	[1]	$ 0.38	[1]	$ 1.18	[1]	$ 0.94	[1]
Diluted	$ 0.41	[1]	$ 0.38	[1]	$ 1.16	[1]	$ 0.93	[1]
Weighted average shares outstanding (1):
Basic	45,834	[1]	42,177	[1]	45,693	[1]	39,767	[1]
Diluted	46,296	[1]	42,546	[1]	46,334	[1]	40,203	[1]

[1] All applicable share and per-share amounts reflect the retroactive effects of the three-for-two common stock split in the form of a stock dividend that was effective May 20, 2011.