Derivative Financial Instruments - Additional Information (Detail) (Allstate Life Insurance Company, USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2013	Dec. 31, 2012
Interest credited to contractholder funds
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) from valuation and settlements on embedded derivative financial instruments	$ 36.9	$ 186.6
Contract benefits
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) from valuation and settlements on embedded derivative financial instruments	$ 10.2	$ 5.1

Amount of realized and unrealized gain (loss) of derivative instruments not designated or qualifying as hedging instruments.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4C

-Subparagraph (e)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624171-113959

Name:	us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration