Segment Information (Total Revenues of Reportable Segments) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 3,129,276	$ 3,039,068	$ 6,138,016	$ 5,551,636
Americas [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	1,794,674	1,799,080	3,582,023	3,238,802
CANADA
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	281,276	300,766	557,358	569,450
EMEA [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	419,325	382,619	817,400	740,009
Asia Pacific [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	579,513	494,616	1,105,195	908,886
Corporate and Other [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	54,488	61,987	76,040	94,489
Life Insurance Product Line [Member] | Americas [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	1,522,698	1,494,003	3,011,201	2,894,820
Life Insurance Product Line [Member] | CANADA
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	269,273	288,912	533,548	546,912
Life Insurance Product Line [Member] | EMEA [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	345,920	301,642	664,006	591,276
Life Insurance Product Line [Member] | Asia Pacific [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	561,529	477,571	1,066,759	871,770
Nontraditional Long-Duration Contracts [Member] | Americas [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	271,976	305,077	570,822	343,982
Nontraditional Long-Duration Contracts [Member] | CANADA
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	12,003	11,854	23,810	22,538
Nontraditional Long-Duration Contracts [Member] | EMEA [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	73,405	80,977	153,394	148,733
Nontraditional Long-Duration Contracts [Member] | Asia Pacific [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 17,984	$ 17,045	$ 38,436	$ 37,116