Insurance (Short-Duration Contracts Historical Claims) (Details)	Dec. 31, 2017
Group Life - Term
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Short-duration Insurance Contracts, Historical Claims Duration, Year One	78.30%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	20.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	0.70%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	0.20%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	0.40%
Short-duration Insurance Contracts, Historical Claims Duration, Year Six	0.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Seven	0.00%
Group Life - Term | Asia
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Short-duration Insurance Contracts, Historical Claims Duration, Year One	23.60%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	25.80%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	13.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	9.30%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	8.60%
Short-duration Insurance Contracts, Historical Claims Duration, Year Six	8.90%
Short-duration Insurance Contracts, Historical Claims Duration, Year Seven	11.30%
Short-duration Insurance Contracts, Historical Claims Duration, Year Eight	5.50%
Group Long-Term Disability
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Short-duration Insurance Contracts, Historical Claims Duration, Year One	4.40%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	18.80%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	13.90%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	8.50%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	7.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Six	6.40%
Short-duration Insurance Contracts, Historical Claims Duration, Year Seven	5.60%
Property & Casualty - Auto
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Short-duration Insurance Contracts, Historical Claims Duration, Year One	39.30%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	31.30%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	14.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	7.90%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	4.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Six	1.80%
Short-duration Insurance Contracts, Historical Claims Duration, Year Seven	0.90%
Short-duration Insurance Contracts, Historical Claims Duration, Year Eight	0.50%
Short-duration Insurance Contracts, Historical Claims Duration, Year Nine	0.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Ten	0.20%
Property & Casualty - Home
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Short-duration Insurance Contracts, Historical Claims Duration, Year One	80.50%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	14.80%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	2.30%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	1.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	0.60%
Short-duration Insurance Contracts, Historical Claims Duration, Year Six	0.30%
Short-duration Insurance Contracts, Historical Claims Duration, Year Seven	0.20%
Short-duration Insurance Contracts, Historical Claims Duration, Year Eight	0.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Nine	0.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Ten	0.10%
Protection Life | Latin America
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Short-duration Insurance Contracts, Historical Claims Duration, Year One	65.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	27.80%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	2.30%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	0.50%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	0.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Six	0.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Seven	0.20%
Short-duration Insurance Contracts, Historical Claims Duration, Year Eight	0.20%
Short-duration Insurance Contracts, Historical Claims Duration, Year Nine	0.60%
Short-duration Insurance Contracts, Historical Claims Duration, Year Ten	1.30%
Protection Health | Latin America
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Short-duration Insurance Contracts, Historical Claims Duration, Year One	86.70%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	11.20%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	0.60%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	0.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	0.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Six	0.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Seven	(0.30%)
Short-duration Insurance Contracts, Historical Claims Duration, Year Eight	0.50%
Short-duration Insurance Contracts, Historical Claims Duration, Year Nine	0.80%
Short-duration Insurance Contracts, Historical Claims Duration, Year Ten	1.40%