Ownership Interests in and Advances to Partner Companies and Funds - Results of Operations for Equity Method Investments (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Equity Method Investments and Joint Ventures [Abstract]
Revenue	$ 320,702	$ 273,764	$ 191,928
Gross profit	102,803	123,234	90,876
Net loss	$ (108,458)	$ (63,452)	$ (79,662)