Note 12 - Employee Benefit and Retirement Plans - Status of the Postretirement Medical and Life Insurance Benefit Plan (Details) - USD ($) $ in Thousands	12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2016
Benefit obligation at beginning of year	$ 175,233	$ 166,189	$ 161,062
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	4.31%			3.77%
Fair value of plan assets at beginning of year	$ 115,015	122,787	122,924
Employer contributions	5,000	4,482	6,049
Benefits paid	(6,902)	(6,590)	(6,524)
Fair value of plan assets at end of year	117,778	115,015	122,787
Current liability	(63)	(45)	(37)
Noncurrent liability	(51,855)	(60,173)	(43,365)
Prior service cost
Accumulated loss	(12,131)	(17,849)	(16,795)
Amounts not yet recognized as a component of net periodic benefit cost	(12,131)	(17,849)	(16,795)
Accumulated net periodic benefit cost in excess of contributions	(39,787)	(42,369)	(26,607)
Net amount recognized in balance sheet	(51,918)	(60,218)	(43,402)
Service cost	1,405	2,757	2,663
Interest cost	6,246	7,032	6,818
Benefits paid	(6,902)	(6,590)	(6,524)
Actuarial (gain) loss	(1,207)	13,670	6,337
Net periodic benefit cost	2,585	21,399	3,824
Prior service cost
Net loss	(26)	(114)	(53)
Benefit obligation at end of year	169,696	175,233	166,189
UNITED STATES
Benefit obligation at beginning of year	$ 130,863	$ 116,398	$ 110,054
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	3.92%	3.77%	4.49%
Fair value of plan assets at beginning of year	$ 81,910	$ 84,853	$ 84,629
Employer contributions	4,045	3,380	4,870
Benefits paid	(5,106)	(4,593)	(4,372)
Fair value of plan assets at end of year	81,928	81,910	84,853
Current liability	(63)	(45)	(37)
Noncurrent liability	$ (42,147)	$ (48,908)	$ (31,508)
Discount rate	3.77%	4.49%	4.29%
Prior service cost
Accumulated loss	(8,254)	(13,412)	(11,817)
Amounts not yet recognized as a component of net periodic benefit cost	(8,254)	(13,412)	(11,817)
Accumulated net periodic benefit cost in excess of contributions	(33,956)	(35,541)	(19,728)
Net amount recognized in balance sheet	(42,210)	(48,953)	(31,545)
Service cost	1,405	2,757	2,663
Interest cost	4,994	5,248	4,839
Benefits paid	(5,106)	(4,593)	(4,372)
Actuarial (gain) loss	(3,848)	11,053	3,214
Net periodic benefit cost	2,460	19,195	2,758
Prior service cost
Net loss	(26)	(114)	(53)
Benefit obligation at end of year	124,138	130,863	116,398
Post Retirement Medical and Life Insurance Plan [Member] | UNITED STATES
Benefit obligation at beginning of year	$ 7,381	$ 6,611	$ 5,867
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	3.92%	3.77%	4.49%
Rate of compensation increase	2.64%	2.64%	2.64%
Fair value of plan assets at beginning of year
Employer contributions	483	772	647
Benefits paid	(483)	(772)	(647)
Fair value of plan assets at end of year
Current liability	(370)	(396)	(441)
Noncurrent liability	$ (6,716)	$ (6,985)	$ (6,170)
Discount rate	3.77%	4.49%	4.29%
Rate of compensation increase	2.64%	2.64%	2.64%
Prior service cost	$ 3,851	$ 4,523	$ 5,305
Accumulated loss	(1,696)	(1,983)	(850)
Amounts not yet recognized as a component of net periodic benefit cost	2,155	2,540	4,455
Accumulated net periodic benefit cost in excess of contributions	(9,241)	(9,921)	(11,066)
Net amount recognized in balance sheet	(7,086)	(7,381)	(6,611)
Service cost	85	105	113
Interest cost	269	287	244
Benefits paid	(483)	(772)	(647)
Actuarial (gain) loss	(166)	1,150	1,034
Prior service cost	(673)	(781)	(799)
Amortization of accumulated loss	121	15
Net periodic benefit cost	(198)	(374)	(442)
Prior service cost	537	673	781
Net loss	(99)	(120)	(15)
Benefit obligation at end of year	7,086	7,381	6,611
	$ 438	$ 553	$ 766
Healthcare cost trend rate assumed for next year	6.60%	6.90%	8.00%
Rate to which the cost trend rate gradually declines	4.50%	4.50%	4.50%
Year that the rate reaches the rate at which it is assumed to remain	2037	2037	2028