Retirement and Compensation Plans FBL's share of prepaid or accrued pension costs (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Multiemployer unrecognized liability for underfunded status	$ 45,400	$ 57,100
United States Pension Plan of US Entity [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	26,006	20,258
Pension and Other Postretirement Defined Benefit Plans, Liabilities	0	0
Defined Benefit Plan, Amounts Recognized in Balance Sheet	26,006	20,258
Other Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assets for Plan Benefits	876	969
Pension and Other Postretirement Defined Benefit Plans, Liabilities	(19,159)	(16,746)
Defined Benefit Plan, Amounts Recognized in Balance Sheet	(18,283)	(15,777)
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Gains (Losses), before Tax	12,094	9,695
Defined Benefit Plan, Accumulated Other Comprehensive Income Net Prior Service Cost Credit, after Tax	0	(1)
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax	$ 12,094	$ 9,694