Fair Value Measurements (Assets Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs) (Details) (USD $)	3 Months Ended	12 Months Ended
	Sep. 30, 2011	Dec. 31, 2011
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Cost method investment, carrying value of impaired investment	$ 5,000,000
Cost method investments, fair value of impaired investment	1,500,000
Cost method investment, impairment charge	3,500,000	3,500,000
Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at December 31, 2010		49,340,000
Purchases of Level 3 securities		3,696,000
Proceeds received on Level 3 securities		(50,000,000)	[1]
Decrease in previously recognized unrealized losses included in accumulated other comprehensive income		660,000
Balance at December 31, 2011		$ 3,696,000

[1] In September 2011, the Company's investment in the AIG Capped Floater matured and proceeds of $50.0 million were received. See Note 4 for more information regarding the AIG Capped Floater.