Commitments, Guarantees and Contingent Liabilities (Details 3) $ in Millions							1 Months Ended	12 Months Ended		24 Months Ended
	Jan. 27, 2017 claim case	Nov. 22, 2016 claim plaintiff	Sep. 02, 2016 claim	May 20, 2016 plaintiff	Jan. 28, 2016 plaintiff defense	Jun. 17, 2015 plaintiff	Dec. 31, 2007 claim	Dec. 31, 2016 USD ($) claim opinion	Dec. 31, 2001 employee	Dec. 31, 2016 USD ($) claim opinion plaintiff defense	Jan. 26, 2017 opinion	Apr. 08, 2016 adjuster	Dec. 31, 2015 USD ($) trial
Guarantees:
Limitations or indemnifications of reinsurance agreements								$ 0		$ 0
Proceedings:
Number of former employee agents plaintiffs seek benefits for | employee									6,300
Loss contingency, number of plaintiffs (in plaintiffs, in cases)		1		499	10	10			32	459
Number of defenses | defense					2					2
Loss contingency, number of trials | trial													2
Reserves for asbestos claims								912		$ 912			$ 960
Reinsurance recoverables for asbestos claims								444		444			458
Reserves for environmental claims								179		179			179
Reinsurance recoverables for environmental claims								$ 40		$ 40			$ 43
Percentage of net asbestos and environmental reserves that were for incurred but not reported estimated losses								57.00%		57.00%			57.00%
Number of class action cases | claim			2				2
Loss contingency, pending claims, adjusters omitted, number | adjuster												50
Number of cases pending (in adjusters, in claims) | claim		2
Loss contingency, number of claims, loss is not probable | claim								3		3
Loss contingency, opinions, number | opinion								3		3
Minimum
Proceedings:
Loss contingencies, reasonably possible pretax loss exposure in excess of the amount accrued								$ 0
Maximum
Proceedings:
Loss contingencies, reasonably possible pretax loss exposure in excess of the amount accrued								875
Residual guarantee
Guarantees:
Potential leased automobiles residual value								$ 46		$ 46
Guarantee obligations term, low end of range								1 year
Guarantee obligations term, high end of range								4 years
Adjuster Opted Out
Proceedings:
Number of cases pending (in adjusters, in claims) | adjuster												11
Fair Labor Standards Act
Proceedings:
Number of cases pending (in adjusters, in claims) | adjuster												105
New York Labor Law
Proceedings:
Number of cases pending (in adjusters, in claims) | adjuster												137
Against Allstate
Proceedings:
Loss contingency, opinions, number | opinion								2		2
In Favor of Allstate
Proceedings:
Loss contingency, opinions, number | opinion								1		1
Signed Releases Knowingly and Voluntarily | Judicial Ruling
Proceedings:
Loss contingency, number of plaintiffs (in plaintiffs, in cases) | plaintiff						2
Did Not Sign Releases Knowingly and Voluntarily | Judicial Ruling
Proceedings:
Loss contingency, number of plaintiffs (in plaintiffs, in cases) | plaintiff						8
Subsequent Event
Proceedings:
Loss contingency, number of plaintiffs (in plaintiffs, in cases) | case	3
Loss contingency, opinions, number | opinion											2
Subsequent Event | Randy Rosenberg, et al
Proceedings:
Number of class action cases | claim	1