Supplemental Schedule of Reinsurance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Direct Premiums, Life Insurance in Force	$ 1,576,000	$ 1,686,000	$ 78,000
Ceded Premiums, Life Insurance in Force	214,727,000	222,388,000	230,544,000
Assumed Premiums, Life Insurance in Force	3,062,525,000	2,995,079,000	2,943,517,000
Premiums, Net, Life Insurance in Force	$ 2,849,374,000	$ 2,774,377,000	$ 2,713,051,000
Life Insurance in Force Premiums, Percentage Assumed to Net	107.50%	108.00%	108.50%
Direct Premiums Earned	$ 57,562	$ 43,106	$ 19,365
Reinsurance Premiums for Insurance Companies, by Product Segment, Amount Ceded to Other Companies	858,278	843,673	447,889
Assumed Premiums Earned	10,049,587	9,371,308	9,098,378
Reinsurance Premiums for Insurance Companies, by Product Segment, Net Amount	$ 9,248,871	$ 8,570,741	$ 8,669,854
Reinsurance Premiums for Insurance Companies, by Product Segment, Percentage of Amount Assumed to Net	108.70%	109.30%	104.90%
US Traditional Segment Reporting Information [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Direct Premiums Earned	$ 31,600	$ 29,400	$ 9,600
Reinsurance Premiums for Insurance Companies, by Product Segment, Amount Ceded to Other Companies	616,000	607,000	287,800
Assumed Premiums Earned	5,834,000	5,384,300	5,003,700
Reinsurance Premiums for Insurance Companies, by Product Segment, Net Amount	$ 5,249,600	$ 4,806,700	$ 4,725,500
Reinsurance Premiums for Insurance Companies, by Product Segment, Percentage of Amount Assumed to Net	111.10%	112.00%	105.90%
US Non-Traditional Segment Reporting Information [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Direct Premiums Earned	$ 1,600	$ 2,900	$ 0
Reinsurance Premiums for Insurance Companies, by Product Segment, Amount Ceded to Other Companies	40,200	38,800	39,400
Assumed Premiums Earned	63,000	58,100	59,500
Reinsurance Premiums for Insurance Companies, by Product Segment, Net Amount	$ 24,400	$ 22,200	$ 20,100
Reinsurance Premiums for Insurance Companies, by Product Segment, Percentage of Amount Assumed to Net	258.20%	261.70%	296.00%
Canada Traditional Segment Reporting Information [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Direct Premiums Earned	$ 0	$ 0	$ 0
Reinsurance Premiums for Insurance Companies, by Product Segment, Amount Ceded to Other Companies	36,500	42,300	49,600
Assumed Premiums Earned	965,100	881,200	1,002,900
Reinsurance Premiums for Insurance Companies, by Product Segment, Net Amount	$ 928,600	$ 838,900	$ 953,300
Reinsurance Premiums for Insurance Companies, by Product Segment, Percentage of Amount Assumed to Net	103.90%	105.00%	105.20%
Canada Non-Traditional Segment Reporting Information [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Direct Premiums Earned	$ 0	$ 0	$ 0
Reinsurance Premiums for Insurance Companies, by Product Segment, Amount Ceded to Other Companies	0	0	0
Assumed Premiums Earned	38,700	38,000	21,300
Reinsurance Premiums for Insurance Companies, by Product Segment, Net Amount	$ 38,700	$ 38,000	$ 21,300
Reinsurance Premiums for Insurance Companies, by Product Segment, Percentage of Amount Assumed to Net	100.00%	100.00%	100.00%
EMEA Traditional Segment Reporting Information [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Direct Premiums Earned	$ 24,100	$ 10,700	$ 9,800
Reinsurance Premiums for Insurance Companies, by Product Segment, Amount Ceded to Other Companies	30,900	25,500	30,400
Assumed Premiums Earned	1,146,900	1,136,300	1,178,000
Reinsurance Premiums for Insurance Companies, by Product Segment, Net Amount	$ 1,140,100	$ 1,121,500	$ 1,157,400
Reinsurance Premiums for Insurance Companies, by Product Segment, Percentage of Amount Assumed to Net	100.60%	101.30%	101.80%
EMEA Non-Traditional Segment Reporting Information [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Direct Premiums Earned	$ 300	$ 100	$ 0
Reinsurance Premiums for Insurance Companies, by Product Segment, Amount Ceded to Other Companies	84,400	89,100	0
Assumed Premiums Earned	264,400	260,800	216,600
Reinsurance Premiums for Insurance Companies, by Product Segment, Net Amount	$ 180,300	$ 171,800	$ 216,600
Reinsurance Premiums for Insurance Companies, by Product Segment, Percentage of Amount Assumed to Net	146.60%	151.80%	100.00%
Asia Pacific Traditional Segment Reporting Information [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Direct Premiums Earned	$ 0	$ 0	$ 0
Reinsurance Premiums for Insurance Companies, by Product Segment, Amount Ceded to Other Companies	50,300	41,000	40,700
Assumed Premiums Earned	1,731,800	1,592,600	1,581,600
Reinsurance Premiums for Insurance Companies, by Product Segment, Net Amount	$ 1,681,500	$ 1,551,600	$ 1,540,900
Reinsurance Premiums for Insurance Companies, by Product Segment, Percentage of Amount Assumed to Net	103.00%	102.60%	102.60%
Asia Pacific Non-Traditional Segment Reporting Information [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Direct Premiums Earned	$ 0	$ 0	$ 0
Reinsurance Premiums for Insurance Companies, by Product Segment, Amount Ceded to Other Companies	0	0	0
Assumed Premiums Earned	5,400	19,500	34,000
Reinsurance Premiums for Insurance Companies, by Product Segment, Net Amount	$ 5,400	$ 19,500	$ 34,000
Reinsurance Premiums for Insurance Companies, by Product Segment, Percentage of Amount Assumed to Net	100.00%	100.00%	100.00%
Corporate And Other Segment Reporting Information [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Direct Premiums Earned	$ 0	$ 0	$ 0
Reinsurance Premiums for Insurance Companies, by Product Segment, Amount Ceded to Other Companies	0	0	0
Assumed Premiums Earned	300	500	800
Reinsurance Premiums for Insurance Companies, by Product Segment, Net Amount	$ 300	$ 500	$ 800
Reinsurance Premiums for Insurance Companies, by Product Segment, Percentage of Amount Assumed to Net	100.00%	100.00%	100.00%