Segment Information (Total Revenues of Reportable Segments) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 3,420,031	$ 3,173,707
Americas [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	1,795,326	1,703,046
CANADA
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	335,907	315,096
EMEA [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	493,427	481,925
Asia Pacific [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	727,700	634,385
Corporate and Other [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	67,671	39,255
Life Insurance Product Line [Member] | Americas [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	1,540,666	1,489,694
Life Insurance Product Line [Member] | CANADA
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	312,333	302,319
Life Insurance Product Line [Member] | EMEA [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	384,006	393,782
Life Insurance Product Line [Member] | Asia Pacific [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	673,172	614,539
Nontraditional Long-Duration Contracts [Member] | Americas [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	254,660	213,352
Nontraditional Long-Duration Contracts [Member] | CANADA
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	23,574	12,777
Nontraditional Long-Duration Contracts [Member] | EMEA [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	109,421	88,143
Nontraditional Long-Duration Contracts [Member] | Asia Pacific [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 54,528	$ 19,846