Unpaid Losses and Loss Expenses and Policy Benefits for Life and Annuity Contracts Reconciliation of losses and loss expenses including life policy benefits (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reconciliation of loss and loss expense
Losses and loss expenses and life policy benefits	$ 767,000	$ 804,000	$ 865,000	$ 721,000	$ 870,000	$ 960,000	$ 884,000	$ 749,000	$ 3,157,420	$ 3,462,770	$ 3,157,808
Non Life [Member]
Reconciliation of loss and loss expense
Losses and loss expenses and life policy benefits									2,192,999	2,462,568	2,397,256
Life and Health [Member]
Reconciliation of loss and loss expense
Losses and loss expenses and life policy benefits									$ 964,421	$ 1,000,202	$ 760,552