Information Services Contracts (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Information Services Contracts [Line Items]
Information service contract payments	$ 13,038	$ 13,426	$ 15,529
2012 [Member]
Information Services Contracts [Line Items]
Information service contract payments	13,000
2013 [Member]
Information Services Contracts [Line Items]
Information service contract payments	10,500
2014 [Member]
Information Services Contracts [Line Items]
Information service contract payments	8,000
2015 [Member]
Information Services Contracts [Line Items]
Information service contract payments	7,000
2016 [Member]
Information Services Contracts [Line Items]
Information service contract payments	7,000
2017 [Member]
Information Services Contracts [Line Items]
Information service contract payments	$ 7,000