Employee Benefit Plans (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) $ / Family	Dec. 31, 2018 USD ($)	Jun. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)	Jun. 30, 2017 USD ($)
Defined Benefit Plan Disclosure [Line Items]
401(k) deferred compensation and profit sharing plan, company contributions	$ 1,755	$ 1,438		$ 1,328
Annual losses per covered family | $ / Family	175
Annual deductible per covered family | $ / Family	300
Charges to earnings for self-insurance reserve	$ 5,495	3,724		4,192
Pension expense	84	72
River Valley | Pentegra DB Plan
Defined Benefit Plan Disclosure [Line Items]
Total contributions under defined benefit plan as reported on Form 5500			$ 164,570		$ 367,119
Multiemployer plan, maximum percentage of employer's contributions			5.00%
Postretirement Medical and Life Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Estimated future employer contributions in 2020	96
Certain directors and officers
Defined Benefit Plan Disclosure [Line Items]
Accrued benefits payable	2,043	2,046
Deferred compensation expense	$ 243	$ 324		$ 187