Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2019	Feb. 28, 2020	Jun. 30, 2019
Document and Entity Information
Entity Interactive Data Current	Yes
Entity Incorporation, State or Country Code	IL
Entity Registrant Name	ALLSTATE LIFE INSURANCE CO
Entity Central Index Key	0000352736
Document Type	10-K
Document Annual Report	true
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Period End Date	Dec. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)		23,800
Entity Public Float			$ 0
Entity Tax Identification Number	36-2554642
Document Transition Report	false
Entity File Number	0-31248
Entity Address, Address Line One	3075 Sanders Road
Entity Address, City or Town	Northbrook
Entity Address, State or Province	IL
Entity Address, Postal Zip Code	60062
City Area Code	847
Local Phone Number	402-5000