SOI Proceeds from sales (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Proceeds from sales	[1]	$ 4,541,303	$ 4,187,547	$ 2,705,999
Gross realized gains from sales		84,305	47,965	47,852
Gross realized losses from sales		$ 16,858	$ 6,476	$ 1,229

[1] Includes gains (losses) on the hedged asset for fair value hedges.