Segment Information (Total Assets of Reportable Segments) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 58,138,072	$ 53,097,879
Americas [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	34,959,162	31,852,931
CANADA
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	4,070,039	3,932,087
EMEA [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	6,869,097	6,435,255
Asia Pacific [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	5,628,360	4,644,362
Corporate and Other [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	6,611,414	6,233,244
Life Insurance Product Line [Member] | Americas [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	18,588,924	18,140,825
Life Insurance Product Line [Member] | CANADA
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	3,965,235	3,846,682
Life Insurance Product Line [Member] | EMEA [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	2,852,309	2,559,124
Life Insurance Product Line [Member] | Asia Pacific [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	4,449,350	3,968,081
Nontraditional Long-Duration Contracts [Member] | Americas [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	16,370,238	13,712,106
Nontraditional Long-Duration Contracts [Member] | CANADA
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	104,804	85,405
Nontraditional Long-Duration Contracts [Member] | EMEA [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	4,016,788	3,876,131
Nontraditional Long-Duration Contracts [Member] | Asia Pacific [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 1,179,010	$ 676,281