Subsequent Events Impact of change in stock price (Details) (USD $)	12 Months Ended			3 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Mar. 31, 2014 Forecast Fair value accounting Parent Equity Warrant Asset, Public Portfolio Subsequent Event	Mar. 31, 2014 Forecast Fair value accounting With sales restrictions discount Subsequent Event	Mar. 31, 2014 Forecast Fair value accounting With sales restrictions discount Parent Subsequent Event	Mar. 31, 2014 Forecast Fair value accounting With sales restrictions discount Parent Non-marketable securities Subsequent Event	Mar. 31, 2014 Forecast Fair value accounting With sales restrictions discount Noncontrolling Interest [Member] Non-marketable securities Subsequent Event	Mar. 31, 2014 Forecast Fair value accounting Without sales restrictions discount Subsequent Event	Mar. 31, 2014 Forecast Fair value accounting Without sales restrictions discount Parent Subsequent Event	Mar. 31, 2014 Forecast Fair value accounting Without sales restrictions discount Parent Non-marketable securities Subsequent Event	Mar. 31, 2014 Forecast Fair value accounting Without sales restrictions discount Noncontrolling Interest [Member] Non-marketable securities Subsequent Event	Dec. 31, 2013 FireEye	Feb. 25, 2014 FireEye Subsequent Event
Subsequent Event [Line Items]
Closing stock price, in dollars per share	$ 104.86												$ 43.61	$ 80.00
Gain (loss) on specified investments and derivative instruments, pretax						$ 53,000,000				$ 63,000,000
Gains on derivative instruments, net	42,184,000	18,679,000	36,798,000	13,000,000
Gains on investment securities, net	$ 419,408,000	$ 122,114,000	$ 195,034,000		$ 200,000,000		$ 40,000,000	$ 160,000,000	$ 250,000,000		$ 50,000,000	$ 200,000,000