Schedule VI Supplemental Information Concerning Property and Casualty Insurance Operations Level 4 (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Period Increase (Decrease)	$ 228		$ 192		$ (4)
Weighted Average Discount Rate, Percent					4.00%
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	$ 556	[1]	$ 553	[1]	$ 538	[1]
Workers Compensation [Member]
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Weighted Average Discount Rate, Percent	3.50%		3.50%

[1] Reserves for permanently disabled claimants have been discounted using the weighted average interest rates of 3.5%, 3.5%, and 4.0% for the years ended December 31, 2014, 2013, and 2012, respectively.