Unpaid Losses and Loss Expenses and Policy Benefits for Life and Annuity Contracts Non Life loss and loss expenses rollforward (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Non-Life loss and loss expenses rollforward [Abstract]
Gross liability at beginning of year	$ 9,745,806	$ 10,646,318	$ 10,709,371
Reinsurance recoverable at beginning of year	214,349	267,384	291,330
Net liability at beginning of year	9,531,457	10,378,934	10,418,041
Current year	3,023,704	3,122,981	3,118,755
Prior years	(830,705)	(660,413)	(721,499)
Total Non-life Incurred Claims	2,192,999	2,462,568	2,397,256
Change in Paris Re Reserve Agreement	(8,771)	(25,412)	(49,544)
Current year	250,720	267,806	242,053
Prior years	2,171,883	2,530,743	2,159,506
Total Non-life Claims Paid	2,422,603	2,798,549	2,401,559
Effects of foreign exchange rate changes	(417,605)	(486,084)	14,740
Net liability at end of year	8,875,477	9,531,457	10,378,934
Reinsurance recoverable at end of year	189,234	214,349	267,384
Gross liability at end of year	$ 9,064,711	$ 9,745,806	$ 10,646,318