Commitments and Contingencies (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2012	Dec. 31, 2012
Commitments and Contingencies
Amount reimbursed for individual claims under stop loss agreement, minimum		$ 140
Amount reimbursed for aggregate claims under stop loss agreement, minimum		9,303
Aggregate claims paid under stop loss agreement	6,563
Aggregate claims paid under stop loss agreement related to Company	1,484
Liability for claims incurred but not paid and estimated claims incurred but not reported	227
Minimum
Commitments and Contingencies
Minimum notice period for termination of service agreements with TPA (in days)	25 days
Guarantees | Credit facility
Commitments and Contingencies
Guarantee amount	535,000
Guarantees | Mortgage loans
Commitments and Contingencies
Guarantee amount	$ 17,030