Supplementary Insurance Information (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Supplementary Insurance Information, by Segment [Line Items]
Supplementary Insurance Information, Deferred Policy Acquisition Costs		$ 3,338,605	$ 3,392,437
Supplementary Insurance Information, Liability for Future Policy Benefits, Losses, Claims and Loss Expense Reserves		33,610,927	33,276,124
Supplementary Insurance Information, Other Policy Claims and Benefits Payable		4,263,026	4,094,640
Supplementary Insurance Information, Premium Revenue		9,248,871	8,570,741	$ 8,669,854
Supplementary Insurance Information, Net Investment Income		1,911,886	1,734,495	1,713,691
Supplementary Insurance Information, Benefits, Claims, Losses and Settlement Expense		8,358,066	7,826,346	7,857,672
Supplementary Insurance Information, Amortization of Deferred Policy Acquisition Costs	[1]	381,192	229,876	979,365
Supplementary Insurance Information, Other Operating Expense		1,738,307	1,617,161	1,058,624
US Traditional Segment Reporting Information [Member]
Supplementary Insurance Information, by Segment [Line Items]
Supplementary Insurance Information, Deferred Policy Acquisition Costs		1,818,211	1,807,407
Supplementary Insurance Information, Liability for Future Policy Benefits, Losses, Claims and Loss Expense Reserves		10,990,560	10,593,424
Supplementary Insurance Information, Other Policy Claims and Benefits Payable		1,659,473	1,681,130
Supplementary Insurance Information, Premium Revenue		5,249,571	4,806,706	4,725,505
Supplementary Insurance Information, Net Investment Income		699,833	636,779	552,805
Supplementary Insurance Information, Benefits, Claims, Losses and Settlement Expense		4,717,850	4,444,196	4,181,492
Supplementary Insurance Information, Amortization of Deferred Policy Acquisition Costs	[1]	177,255	131,439	467,067
Supplementary Insurance Information, Other Operating Expense		698,762	653,620	283,064
US Non-Traditional Segment Reporting Information [Member]
Supplementary Insurance Information, by Segment [Line Items]
Supplementary Insurance Information, Deferred Policy Acquisition Costs		582,031	691,944
Supplementary Insurance Information, Liability for Future Policy Benefits, Losses, Claims and Loss Expense Reserves		13,074,231	12,882,145
Supplementary Insurance Information, Other Policy Claims and Benefits Payable		20,352	16,430
Supplementary Insurance Information, Premium Revenue		24,349	22,177	20,079
Supplementary Insurance Information, Net Investment Income		631,097	566,180	644,285
Supplementary Insurance Information, Benefits, Claims, Losses and Settlement Expense		333,107	310,464	402,387
Supplementary Insurance Information, Amortization of Deferred Policy Acquisition Costs	[1]	133,501	40,416	203,605
Supplementary Insurance Information, Other Operating Expense		90,458	85,022	105,207
Canada Traditional Segment Reporting Information [Member]
Supplementary Insurance Information, by Segment [Line Items]
Supplementary Insurance Information, Deferred Policy Acquisition Costs		201,149	197,243
Supplementary Insurance Information, Liability for Future Policy Benefits, Losses, Claims and Loss Expense Reserves		2,713,510	2,498,385
Supplementary Insurance Information, Other Policy Claims and Benefits Payable		200,246	160,478
Supplementary Insurance Information, Premium Revenue		928,642	838,894	953,389
Supplementary Insurance Information, Net Investment Income		178,927	182,621	193,610
Supplementary Insurance Information, Benefits, Claims, Losses and Settlement Expense		707,428	670,477	784,470
Supplementary Insurance Information, Amortization of Deferred Policy Acquisition Costs	[1]	10,621	11,299	190,164
Supplementary Insurance Information, Other Operating Expense		265,250	217,061	83,446
Canada Non-Traditional Segment Reporting Information [Member]
Supplementary Insurance Information, by Segment [Line Items]
Supplementary Insurance Information, Deferred Policy Acquisition Costs		0	0
Supplementary Insurance Information, Liability for Future Policy Benefits, Losses, Claims and Loss Expense Reserves		29,531	26,547
Supplementary Insurance Information, Other Policy Claims and Benefits Payable		4,599	2,829
Supplementary Insurance Information, Premium Revenue		38,701	37,969	21,192
Supplementary Insurance Information, Net Investment Income		2,692	1,436	2,595
Supplementary Insurance Information, Benefits, Claims, Losses and Settlement Expense		36,275	29,251	20,116
Supplementary Insurance Information, Amortization of Deferred Policy Acquisition Costs	[1]	0	0	0
Supplementary Insurance Information, Other Operating Expense		2,718	1,881	1,969
EMEA Traditional Segment Reporting Information [Member]
Supplementary Insurance Information, by Segment [Line Items]
Supplementary Insurance Information, Deferred Policy Acquisition Costs		206,837	236,194
Supplementary Insurance Information, Liability for Future Policy Benefits, Losses, Claims and Loss Expense Reserves		913,351	1,104,771
Supplementary Insurance Information, Other Policy Claims and Benefits Payable		740,218	754,573
Supplementary Insurance Information, Premium Revenue		1,140,062	1,121,540	1,157,407
Supplementary Insurance Information, Net Investment Income		50,301	51,370	52,086
Supplementary Insurance Information, Benefits, Claims, Losses and Settlement Expense		999,005	979,225	1,013,331
Supplementary Insurance Information, Amortization of Deferred Policy Acquisition Costs	[1]	33,795	39,164	43,549
Supplementary Insurance Information, Other Operating Expense		132,290	123,943	117,864
EMEA Non-Traditional Segment Reporting Information [Member]
Supplementary Insurance Information, by Segment [Line Items]
Supplementary Insurance Information, Deferred Policy Acquisition Costs		0	0
Supplementary Insurance Information, Liability for Future Policy Benefits, Losses, Claims and Loss Expense Reserves		3,457,196	3,994,702
Supplementary Insurance Information, Other Policy Claims and Benefits Payable		46,761	35,801
Supplementary Insurance Information, Premium Revenue		180,271	171,830	216,562
Supplementary Insurance Information, Net Investment Income		125,282	73,432	55,043
Supplementary Insurance Information, Benefits, Claims, Losses and Settlement Expense		178,014	161,917	204,110
Supplementary Insurance Information, Amortization of Deferred Policy Acquisition Costs	[1]	0	0	0
Supplementary Insurance Information, Other Operating Expense		24,497	16,304	17,351
Asia Pacific Traditional Segment Reporting Information [Member]
Supplementary Insurance Information, by Segment [Line Items]
Supplementary Insurance Information, Deferred Policy Acquisition Costs		512,123	457,372
Supplementary Insurance Information, Liability for Future Policy Benefits, Losses, Claims and Loss Expense Reserves		1,288,642	1,115,987
Supplementary Insurance Information, Other Policy Claims and Benefits Payable		1,563,707	1,420,248
Supplementary Insurance Information, Premium Revenue		1,681,505	1,551,586	1,540,910
Supplementary Insurance Information, Net Investment Income		83,049	80,549	84,489
Supplementary Insurance Information, Benefits, Claims, Losses and Settlement Expense		1,345,951	1,208,984	1,208,611
Supplementary Insurance Information, Amortization of Deferred Policy Acquisition Costs	[1]	24,597	7,373	74,571
Supplementary Insurance Information, Other Operating Expense		286,674	316,346	312,652
Asia Pacific Non-Traditional Segment Reporting Information [Member]
Supplementary Insurance Information, by Segment [Line Items]
Supplementary Insurance Information, Deferred Policy Acquisition Costs		18,254	2,277
Supplementary Insurance Information, Liability for Future Policy Benefits, Losses, Claims and Loss Expense Reserves		641,614	758,301
Supplementary Insurance Information, Other Policy Claims and Benefits Payable		19,643	14,634
Supplementary Insurance Information, Premium Revenue		5,428	19,474	34,030
Supplementary Insurance Information, Net Investment Income		23,648	18,678	17,972
Supplementary Insurance Information, Benefits, Claims, Losses and Settlement Expense		37,976	20,766	42,351
Supplementary Insurance Information, Amortization of Deferred Policy Acquisition Costs	[1]	1,423	185	409
Supplementary Insurance Information, Other Operating Expense		19,920	16,011	15,829
Corporate And Other Segment Reporting Information [Member]
Supplementary Insurance Information, by Segment [Line Items]
Supplementary Insurance Information, Deferred Policy Acquisition Costs		0	0
Supplementary Insurance Information, Liability for Future Policy Benefits, Losses, Claims and Loss Expense Reserves		502,292	301,862
Supplementary Insurance Information, Other Policy Claims and Benefits Payable		8,027	8,517
Supplementary Insurance Information, Premium Revenue		342	565	780
Supplementary Insurance Information, Net Investment Income		117,057	123,450	110,806
Supplementary Insurance Information, Benefits, Claims, Losses and Settlement Expense		2,460	1,066	804
Supplementary Insurance Information, Amortization of Deferred Policy Acquisition Costs	[1]	0	0	0
Supplementary Insurance Information, Other Operating Expense		$ 217,738	$ 186,973	$ 121,242

[1] During 2015, the Company enhanced its process to track certain DAC components. See Note 8 - “Deferred Policy Acquisition Costs” in the Notes to Consolidated Financial Statements for additional information.