Segment Information (Total Revenues of Reportable Segments) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 3,145,310	$ 2,900,577	$ 9,283,326	$ 8,452,213
Americas [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	1,785,553	1,721,052	5,367,576	4,959,854
CANADA
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	293,525	293,318	850,883	862,768
EMEA [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	438,013	388,822	1,255,413	1,128,831
Asia Pacific [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	578,592	446,684	1,683,787	1,355,570
Corporate and Other [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	49,627	50,701	125,667	145,190
Life Insurance Product Line [Member] | Americas [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	1,521,383	1,444,917	4,532,584	4,339,737
Life Insurance Product Line [Member] | CANADA
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	281,095	280,959	814,643	827,871
Life Insurance Product Line [Member] | EMEA [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	360,972	289,070	1,024,978	880,346
Life Insurance Product Line [Member] | Asia Pacific [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	561,660	427,647	1,628,419	1,299,417
Nontraditional Long-Duration Contracts [Member] | Americas [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	264,170	276,135	834,992	620,117
Nontraditional Long-Duration Contracts [Member] | CANADA
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	12,430	12,359	36,240	34,897
Nontraditional Long-Duration Contracts [Member] | EMEA [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	77,041	99,752	230,435	248,485
Nontraditional Long-Duration Contracts [Member] | Asia Pacific [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 16,932	$ 19,037	$ 55,368	$ 56,153