Schedule VI Supplemental Information Concerning Property and Casualty Insurance Operations Level 4 (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Period Increase (Decrease)		$ 250	$ 228	$ 192
Property, Liability and Casualty Insurance Product Line [Member]
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Supplemental Information for Property, Casualty Insurance Underwriters, Discount Deducted from Reserves	[1]	$ 523	$ 556	$ 553
Accident and Health Insurance Product Line [Member]
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Weighted Average Discount Rate, Percent		3.24%	3.50%	3.50%

[1] Reserves for permanently disabled claimants have been discounted using the weighted average interest rates of 3.24%, 3.50%, and 3.50% for the years ended December 31, 2015, 2014, and 2013, respectively.