Employee Benefit Plans - Components of Net Periodic Benefit Cost and Amounts Recognized in Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2016
Other Postretirement Benefits Plan
Components of net periodic benefit cost
Service cost	$ 609	$ 760	$ 1,388
Interest cost	835	829	1,194
Amortization of net loss	(841)	(630)	(196)
Net periodic benefit cost	(1,154)	(798)	629
Other changes recognized in OCI
Net loss	(70)	(2,377)
Amortization of net loss	840	630
Amortization of prior service (cost) credit	1,757	1,757
Total recognized in OCI	2,527	10
Net periodic benefit cost (credit)	(1,154)	(798)	$ 629
Total recognized in net periodic benefit cost and OCI	1,373	(788)
Farmer Brothers Plan
Components of net periodic benefit cost
Service cost	0	0
Interest cost	5,417	5,277
Expected return on plan assets	(5,490)	(6,067)
Amortization of net loss	1,588	1,875
Net periodic benefit cost	1,515	1,085
Other changes recognized in OCI
Net loss	(6,340)	(9,363)
Amortization of net loss	(1,588)	(1,875)
Total recognized in OCI	(7,928)	(11,238)
Net periodic benefit cost (credit)	1,515	1,085
Total recognized in net periodic benefit cost and OCI	$ (6,413)	$ (10,153)
Weighted average assumptions used to determine benefit obligations
Discount rate	3.80%	3.55%
Expected long-term return on plan assets	6.75%	7.75%
Brewmatic Plan
Components of net periodic benefit cost
Service cost	$ 0	$ 0
Interest cost	149	157
Expected return on plan assets	(161)	(188)
Amortization of net loss	80	102
Net periodic benefit cost	68	71
Other changes recognized in OCI
Net loss	(267)	(519)
Amortization of net loss	(80)	(102)
Total recognized in OCI	(347)	(621)
Net periodic benefit cost (credit)	68	71
Total recognized in net periodic benefit cost and OCI	$ (279)	$ (550)
Weighted average assumptions used to determine benefit obligations
Discount rate	3.80%	3.55%
Expected long-term return on plan assets	6.75%	7.75%
Hourly Employees’ Plan
Components of net periodic benefit cost
Service cost	$ 0	$ 124
Interest cost	163	152
Expected return on plan assets	(173)	(172)
Amortization of net loss	6	53
Net periodic benefit cost	(4)	157
Other changes recognized in OCI
Net loss	(394)	(317)
Amortization of net loss	(6)	(53)
Total recognized in OCI	(400)	(370)
Net periodic benefit cost (credit)	(4)	157
Total recognized in net periodic benefit cost and OCI	$ (404)	$ (213)
Weighted average assumptions used to determine benefit obligations
Discount rate	3.80%	3.55%
Expected long-term return on plan assets	6.75%	7.75%