Financial Instruments (Details 3) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012 item	Dec. 31, 2011
Disclosure About Significant Unobservable Inputs
Investments	$ 20,478	$ 18,310
Level 3
Disclosure About Significant Unobservable Inputs
Fair Value	23,418	80,198
Interest Rate Lock Commitments | Level 3
Disclosure About Significant Unobservable Inputs
Estimated rate of closure (as a percent)	80.00%
Investments | Level 3
Disclosure About Significant Unobservable Inputs
Investments	20,478	18,310
Investments | Level 3 | Market comparable companies | Minimum
Disclosure About Significant Unobservable Inputs
Enterprise value/Revenue multiple	4.3
Discount rate (as a percent)	25.00%
Investments | Level 3 | Market comparable companies | Maximum
Disclosure About Significant Unobservable Inputs
Enterprise value/Revenue multiple	6.7
Discount rate (as a percent)	40.00%
Investments | Level 3 | Market comparable companies | Weighted average
Disclosure About Significant Unobservable Inputs
Enterprise value/Revenue multiple	5.7
Discount rate (as a percent)	22.00%
Investment in FATV
Disclosure About Significant Unobservable Inputs
Investments	17,110	15,863
Investment in FATV | Level 3
Disclosure About Significant Unobservable Inputs
Investments	$ 17,100	$ 15,900
Number of holdings	19
Number of privately held companies	7