Industry Segments (Identifiable Assets by Segment) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated Assets	$ 21,847,052		$ 21,679,239
Operating Segments [Member] | Reinsurance-Global Segment [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated Assets	2,607,238		2,708,090
Operating Segments [Member] | Insurance-International Segment [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated Assets	1,817,696		1,876,347
Operating Segments [Member] | Insurance-Domestic Segment [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated Assets	16,011,219		16,036,513
Intersegment Eliminations and Corporate, Non-Segment [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated Assets	$ 1,410,899	[1]	$ 1,058,289	[1]

[1] {F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOjk1YWZhMDc0NWFiZTQxMzliNWExNjhjZWYxMzc0NGYxfFRleHRTZWxlY3Rpb246MDlEOEY3Qjg0Q0FENUI4MUJBRDA4NEFFRUExMDVFNTcM}