Schedule VI (details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Supplementary Information Concerning Property-Casualty Insurance Operations
Deferred acquisition costs	$ 1,835	$ 1,804	$ 1,792
Claims and claim adjustment expense reserves	49,850	50,895	50,922
Unearned premiums	11,839	11,850	11,241
Earned premiums	23,713	22,637	22,357
Net investment income	2,787	2,716	2,889
Amortization of deferred acquisition costs	3,882	3,821	3,910
Net written premiums	23,904	22,767	22,447
Property casualty [Member]
Supplementary Information Concerning Property-Casualty Insurance Operations
Deferred acquisition costs	1,835	1,804	1,792
Claims and claim adjustment expense reserves	49,824	50,865	50,888	51,353
Discount from reserves for unpaid claims	1,080	1,090	1,088
Unearned premiums	11,839	11,850	11,241
Earned premiums	23,713	22,637	22,357
Net investment income	2,787	2,716	2,889
Claims and claim adjustment expenses incurred related to current year	14,621	14,060	15,559
Claims and claim adjustment expenses incurred related to prior year	(957)	(944)	(1,074)
Amortization of deferred acquisition costs	3,882	3,821	3,910
Paid claims and claim adjustment expenses	13,927	13,962	14,833
Net written premiums	$ 23,904	$ 22,767	$ 22,447