Claims Payable (Details Textual) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Claims Payable (Textual) [Abstract]
Amount that health benefits expense incurred during the year was reduced by for amounts relating to prior years	$ 92,988	$ 106,215	$ 85,317
Reduction in current year health benefits expense due to release of actuarial reserves established in accordance with Actuarial Standards of Practice for moderately adverse conditions relating to prior years	28,749	32,178	34,414
Remaining reduction in health benefits expense incurred during the year related to prior years	$ 64,239	$ 74,037	$ 50,903