Summary of Investments - SOI AFS Proceeds from sales (Details 2.1) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Investments, Debt and Equity Securities [Abstract]
Proceeds from sales	$ 337,206	$ 59,643	$ 2,995,877	$ 2,299,304
Gross realized gains from sales	8,584	2,465	31,935	22,239
Gross realized losses from sales	$ 304	$ 28	$ 324	$ 1,090