Segment Information (Total Assets of Reportable Segments) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 75,773,985	$ 64,535,245
Americas [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	44,557,518	39,106,169
CANADA
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	4,330,131	4,354,792
EMEA [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	9,868,899	8,380,703
Asia Pacific [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	8,112,476	6,861,723
Corporate and Other [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	8,904,961	5,831,858
Life Insurance Product Line [Member] | Americas [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	19,035,387	19,235,781
Life Insurance Product Line [Member] | CANADA
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	4,248,447	4,200,792
Life Insurance Product Line [Member] | EMEA [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	3,774,565	3,643,174
Life Insurance Product Line [Member] | Asia Pacific [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	6,440,974	5,680,978
Nontraditional Long-Duration Contracts [Member] | Americas [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	25,522,131	19,870,388
Nontraditional Long-Duration Contracts [Member] | CANADA
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	81,684	154,000
Nontraditional Long-Duration Contracts [Member] | EMEA [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	6,094,334	4,737,529
Nontraditional Long-Duration Contracts [Member] | Asia Pacific [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 1,671,502	$ 1,180,745