SCHEDULE II - CONDENSED FINANCIAL INFORMATION OF REGISTRANT (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues
Net investment income									$ 3,042	$ 3,156	$ 3,459
Realized capital gains and losses									(90)	30	694
Revenues	$ 9,278	$ 9,221	$ 9,164	$ 8,871	$ 8,691	$ 9,028	$ 8,982	$ 8,952	36,534	35,653	35,239
Expenses
Interest expense									295	292	322
Loss on extinguishment of debt									0	0	1
Other operating expenses									4,106	4,081	4,341
Total costs and expenses									33,785	32,374	30,929
Income tax benefit									877	1,111	1,386
Net income									1,877	2,171	2,850
Preferred stock dividends									116	116	104
Net income applicable to common shareholders	$ 811	$ 491	$ 242	$ 217	$ 460	$ 621	$ 326	$ 648	1,761	2,055	2,746
Other comprehensive income (loss), after-tax
Unrealized net capital gains and losses									433	(1,306)	280
Unrealized foreign currency translation adjustments									10	(58)	(40)
Unrecognized pension and other postretirement benefit cost									(104)	48	(725)
Other comprehensive income (loss), after-tax									339	(1,316)	(485)
Comprehensive income									2,216	855	2,365
Allstate Corporation
Revenues
Net investment income									11	8	3
Realized capital gains and losses									2	0	0
Other income									55	66	67
Revenues									68	74	70
Expenses
Interest expense									295	292	321
Loss on extinguishment of debt									0	0	1
Pension and other postretirement benefit expense									10	(15)	41
Other operating expenses									28	34	38
Total costs and expenses									333	311	401
Loss from operations before income tax benefit and equity in net income of subsidiaries									(265)	(237)	(331)
Income tax benefit									(115)	(108)	(142)
Loss before equity in net income of subsidiaries									(150)	(129)	(189)
Equity in net income of subsidiaries									2,027	2,300	3,039
Net income									1,877	2,171	2,850
Preferred stock dividends									116	116	104
Net income applicable to common shareholders									1,761	2,055	2,746
Other comprehensive income (loss), after-tax
Unrealized net capital gains and losses									433	(1,306)	280
Unrealized foreign currency translation adjustments									10	(58)	(40)
Unrecognized pension and other postretirement benefit cost									(104)	48	(725)
Other comprehensive income (loss), after-tax									339	(1,316)	(485)
Comprehensive income									$ 2,216	$ 855	$ 2,365