Quarterly Financial Information (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Premiums and product charges	$ 82,680	$ 78,117	$ 83,521	$ 80,658	$ 80,224	$ 79,285	$ 81,997	$ 79,595
Net investment income	108,986	101,478	104,894	109,640	83,865	105,757	103,974	101,022	$ 424,998	$ 394,618	$ 415,199
Realized gains (losses) on investments	(2,707)	646	377	9,288	(9,569)	(759)	841	(2,787)	7,604	(12,274)	(3,387)
Revenues	193,561	184,658	192,906	203,556	158,636	188,111	190,449	182,430	774,681	719,626	737,911
Net income attributable to FBL Financial Group, Inc.	$ 34,739	$ 25,129	$ 32,298	$ 34,043	$ 6,415	$ 31,010	$ 32,803	$ 23,565	$ 126,209	$ 93,793	$ 187,305
Earnings per common share	$ 1.40	$ 1.01	$ 1.30	$ 1.37	$ 0.26	$ 1.24	$ 1.31	$ 0.94	$ 5.09	$ 3.76	$ 7.47
Earnings per common share - assuming dilution	$ 1.40	$ 1.01	$ 1.30	$ 1.37	$ 0.26	$ 1.24	$ 1.31	$ 0.94	$ 5.09	$ 3.75	$ 7.47