Significant Accounting Policies (Health Plan Services Health Care Cost) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Health Care Organization Revenue and Expense [Line Items]
Health plan services	$ 2,191,918	$ 2,358,455	$ 4,460,654	$ 4,702,114
Incurred claims related to 2011 and prior [Member]
Health Care Organization Revenue and Expense [Line Items]
Health plan services		7,900		32,900
Incurred claims, Prior Period net [Member]
Health Care Organization Revenue and Expense [Line Items]
Health plan services	$ 0		$ 0