Guarantees and Contingent Liabilities (Details)								1 Months Ended	3 Months Ended	12 Months Ended	27 Months Ended
	Jan. 27, 2017 appeal case	Jan. 26, 2017 claim	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	Mar. 31, 2017 USD ($) claim	Dec. 31, 2001 employee	Mar. 31, 2017 USD ($) claim plaintiff	Dec. 31, 2016 USD ($)	Dec. 31, 2015 trial	Sep. 16, 2014 adjuster
Guarantees:
Limitations or indemnifications of reinsurance agreements									$ 0		$ 0
Proceedings:
Number of class action cases | claim				2				2	2
Loss contingency, pending claims, number | claim			2
Loss contingency, number of claims, loss is not probable | claim									3		3
Loss contingency, number of plaintiffs	3		1		499	10	10			32	459
Number of former employee agents plaintiffs seek benefits for | employee										6,300
Number of defenses | defense						2
Loss contingency, number of trials | trial													2
Reserves for asbestos claims									$ 891,000,000		$ 891,000,000	$ 912,000,000
Reinsurance recoverables for asbestos claims									428,000,000		428,000,000	444,000,000
Reserves for environmental claims									178,000,000		178,000,000	179,000,000
Reinsurance recoverables for environmental claims									$ 39,000,000		$ 39,000,000	$ 40,000,000
Percentage of net asbestos and environmental reserves that were for incurred but not reported estimated losses									57.00%		57.00%
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									725,000,000
Residual guarantee
Guarantees:
Potential leased automobiles residual value									$ 43,000,000		$ 43,000,000
Guarantee obligations term, low end of range									1 year
Guarantee obligations term, high end of range									4 years
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
Randy Rosenberg, et al
Proceedings:
Number of class action cases | claim		1
Signed Releases Knowingly and Voluntarily | Judicial Ruling
Proceedings:
Loss contingency, number of plaintiffs | plaintiff							2
Did Not Sign Releases Knowingly and Voluntarily | Judicial Ruling
Proceedings:
Loss contingency, number of plaintiffs | plaintiff							8