Gross Gains and Losses from Investment Sales (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Investments Debt And Equity Securities [Abstract]
Gross gains	$ 4,831	$ 237	$ 21,329	$ 13,713
Gross losses	(3,615)		(3,969)	(10,624)
Net gain (loss)	$ 1,216	$ 237	$ 17,360	$ 3,089