Segment Information (Total Assets of Reportable Segments) (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 72,043,816	$ 64,535,245
Americas [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	41,840,368	39,106,169
CANADA
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	4,332,517	4,354,792
EMEA [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	9,671,981	8,380,703
Asia Pacific [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	7,957,656	6,861,723
Corporate and Other [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	8,241,294	5,831,858
Life Insurance Product Line [Member] | Americas [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	19,142,106	19,235,781
Life Insurance Product Line [Member] | CANADA
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	4,198,875	4,200,792
Life Insurance Product Line [Member] | EMEA [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	3,755,356	3,643,174
Life Insurance Product Line [Member] | Asia Pacific [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	6,339,047	5,680,978
Nontraditional Long-Duration Contracts [Member] | Americas [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	22,698,262	19,870,388
Nontraditional Long-Duration Contracts [Member] | CANADA
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	133,642	154,000
Nontraditional Long-Duration Contracts [Member] | EMEA [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	5,916,625	4,737,529
Nontraditional Long-Duration Contracts [Member] | Asia Pacific [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 1,618,609	$ 1,180,745