Document and entity information Document - USD ($)	12 Months Ended
	Dec. 31, 2019	Feb. 24, 2020
Document Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2019
Document Transition Report	false
Entity File Number	1-11917
Entity Registrant Name	FBL FINANCIAL GROUP, INC.
Entity Incorporation, State or Country Code	IA
Entity Tax Identification Number	42-1411715
Entity Address, Address Line One	5400 University Avenue,
Entity Address, City or Town	West Des Moines,
Entity Address, State or Province	IA
Entity Address, Postal Zip Code	50266-5997
City Area Code	(515)
Local Phone Number	225-5400
Title of 12(b) Security	Class A common stock, without par value
Trading Symbol	FFG
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float	$ 614,892,725
Entity Central Index Key	0001012771
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Amendment Flag	false
Common Class A
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		24,655,302
Common Class B
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		11,413