Employee Benefit Plans (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($) $ / Family	Dec. 31, 2020 USD ($)	Jun. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)	Jun. 30, 2019 USD ($)
Defined Benefit Plan Disclosure [Line Items]
401(k) deferred compensation and profit sharing plan, company contributions	$ 2,050	$ 1,956		$ 1,755
Annual losses per covered family | $ / Family	175
Charges to earnings for self-insurance reserve	$ 5,520	5,234		5,495
Postretirement Medical and Life Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Estimated future employer contributions in 2022	131
Multi-Employer Pension Plan | Pentegra DB Plan
Defined Benefit Plan Disclosure [Line Items]
Multiemployer plan, total contributions			$ 253,199		$ 138,322
Multiemployer plan, maximum percentage of employer's contributions			5.00%
Multi-Employer Pension Plan | River Valley
Defined Benefit Plan Disclosure [Line Items]
Pension expense	66	42
Certain directors and officers
Defined Benefit Plan Disclosure [Line Items]
Accrued benefits payable	2,279	2,089
Deferred compensation expense	$ 302	$ 304		$ 243