Gross Gains and Losses from Investment Sales (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Investments Debt And Equity Securities [Abstract]
Gross gains	$ 237	$ 7,327	$ 13,713	$ 18,629
Gross losses		(232,962)	(10,624)	(232,962)
Net gain (loss)	$ 237	$ (225,635)	$ 3,089	$ (214,333)