Segment Information (Total Revenues of Reportable Segments) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 3,467,408	$ 3,195,908	$ 6,887,439	$ 6,369,615
Americas [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	1,885,933	1,794,095	3,681,259	3,497,141
CANADA
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	342,071	324,288	677,978	639,384
EMEA [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	483,485	473,213	976,912	955,138
Asia Pacific [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	692,975	588,512	1,420,675	1,222,897
Corporate and Other [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	62,944	15,800	130,615	55,055
Life Insurance Product Line [Member] | Americas [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	1,584,676	1,564,147	3,125,342	3,053,841
Life Insurance Product Line [Member] | CANADA
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	318,142	312,199	630,475	614,518
Life Insurance Product Line [Member] | EMEA [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	369,499	372,538	753,505	766,320
Life Insurance Product Line [Member] | Asia Pacific [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	633,417	570,520	1,306,589	1,185,059
Nontraditional Long-Duration Contracts [Member] | Americas [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	301,257	229,948	555,917	443,300
Nontraditional Long-Duration Contracts [Member] | CANADA
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	23,929	12,089	47,503	24,866
Nontraditional Long-Duration Contracts [Member] | EMEA [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	113,986	100,675	223,407	188,818
Nontraditional Long-Duration Contracts [Member] | Asia Pacific [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 59,558	$ 17,992	$ 114,086	$ 37,838