Short-Duration Contracts (Claims Development) (Details) - Life Insurance Product Line [Member] - USD ($) $ in Thousands		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Claims Development [Line Items]
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net		$ 1,527,827
Asia Pacific [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	[1]	1,138,783
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	[1]	1,725,445
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented	[1]	144,984
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net	[1]	731,646
Americas [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	[1]	1,894,362
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	[1]	2,481,669
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented	[1]	208,874
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net	[1]	796,181
Short-duration Insurance Contracts, Accident Year 2012 [Member] | Asia Pacific [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	[1]	287,941	$ 269,808	$ 247,028	$ 205,303	$ 149,912	$ 54,638
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	[1]	336,901	325,992	317,536	313,862	309,090	230,295
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net		13,196
Short-duration Insurance Contracts, Accident Year 2012 [Member] | Americas [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	[1]	263,565	258,297	252,018	243,890	222,139	109,323
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	[1]	297,688	299,098	298,262	297,037	309,119	$ 322,579
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net		24
Short-duration Insurance Contracts, Accident Year 2013 [Member] | Asia Pacific [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	[1]	289,472	261,359	231,919	159,799	55,175
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	[1]	347,865	333,639	336,531	346,886	324,334
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net		21,310
Short-duration Insurance Contracts, Accident Year 2013 [Member] | Americas [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	[1]	292,067	285,817	277,130	248,828	114,457
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	[1]	336,436	336,552	338,977	332,907	$ 349,262
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net		164
Short-duration Insurance Contracts, Accident Year 2014 [Member] | Asia Pacific [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	[1]	228,405	196,570	150,295	38,241
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	[1]	300,025	294,049	332,718	306,919
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net		27,113
Short-duration Insurance Contracts, Accident Year 2014 [Member] | Americas [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	[1]	349,078	337,081	304,578	128,813
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	[1]	397,151	396,383	411,373	$ 407,953
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net		1,597
Short-duration Insurance Contracts, Accident Year 2015 [Member] | Asia Pacific [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	[1]	185,393	131,364	54,241
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	[1]	277,166	284,871	308,517
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net		44,713
Short-duration Insurance Contracts, Accident Year 2015 [Member] | Americas [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	[1]	407,282	360,658	146,196
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	[1]	465,167	460,917	$ 459,524
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net		3,809
Short-duration Insurance Contracts, Accident Year 2016 [Member] | Asia Pacific [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	[1]	108,310	42,440
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	[1]	228,342	252,197
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net		62,959
Short-duration Insurance Contracts, Accident Year 2016 [Member] | Americas [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	[1]	392,517	184,940
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	[1]	499,785	$ 500,843
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net		23,149
Short-duration Insurance Contracts, Accident Year 2017 [Member] | Asia Pacific [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	[1]	39,262
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	[1]	235,146
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net		140,159
Short-duration Insurance Contracts, Accident Year 2017 [Member] | Americas [Member]
Claims Development [Line Items]
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	[1]	189,853
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	[1]	485,442
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net		$ 200,109

[1] 2012-2016 Unaudited.