Guarantees and Contingent Liabilities (Details)						1 Months Ended				9 Months Ended	12 Months Ended
	Sep. 30, 2017 USD ($) plaintiff	Jan. 27, 2017 appeal case	Jul. 06, 2016 plaintiff	May 02, 2016 plaintiff	Jan. 01, 2015 plaintiff	Jun. 30, 2017 trial plaintiff	Dec. 31, 2016 USD ($) plaintiff	Jun. 30, 2015 plaintiff	Dec. 31, 2007 claim	Sep. 30, 2017 USD ($) claim	Dec. 31, 2001 employee case	Sep. 16, 2014 adjuster
Guarantees:
Limitations or indemnifications of reinsurance agreements | $	$ 0									$ 0
Proceedings:
Number of class action cases									2	2	2
Loss contingency, number of plaintiffs		3	118	498	460			10			32
Loss contingency, number of trials | trial						2
Reserves for asbestos claims | $	908,000,000						$ 912,000,000			$ 908,000,000
Reinsurance recoverables for asbestos claims | $	428,000,000						444,000,000			428,000,000
Reserves for environmental claims | $	175,000,000						179,000,000			175,000,000
Reinsurance recoverables for environmental claims | $	35,000,000						$ 40,000,000			35,000,000
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 | $										300,000,000
Residual guarantee
Guarantees:
Potential leased automobiles residual value | $	$ 32,000,000									$ 32,000,000
Guarantee obligations term, low end of range										1 year
Guarantee obligations term, high end of range										4 years
Judicial Ruling
Proceedings:
Loss contingency, number of plaintiffs | plaintiff						1
Pending Litigation
Proceedings:
Loss contingency, number of plaintiffs | plaintiff	413					8
Fair Labor Standards Act
Proceedings:
Loss contingency, pending claims, number | adjuster												105
New York Labor Law
Proceedings:
Loss contingency, pending claims, number | adjuster												137
Appeal Denied | Judicial Ruling
Proceedings:
Loss contingency, number of appeals | appeal		1
Appeal Granted | Judicial Ruling
Proceedings:
Loss contingency, number of appeals | appeal		2
Signed Releases Knowingly and Voluntarily
Proceedings:
Loss contingency, number of plaintiffs | plaintiff								2
Did Not Sign Releases Knowingly and Voluntarily
Proceedings:
Loss contingency, number of plaintiffs | plaintiff								8
Plaintiffs Asserted Suffered Loss
Proceedings:
Loss contingency, number of plaintiffs | plaintiff							2
Individual Plaintiffs | Pending Litigation
Proceedings:
Loss contingency, number of plaintiffs | plaintiff	82
Individual Plaintiffs | Settled Litigation
Proceedings:
Loss contingency, number of plaintiffs | plaintiff	3
Phase III | Pending Litigation
Proceedings:
Loss contingency, number of plaintiffs | plaintiff	8