Changes in Accounting Principles and Corrections to Previously Issued Financial Statements Schedules of Accounting Adjustments (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2015
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Inventories	$ 104,431				$ 79,790				$ 104,431	$ 79,790
Total assets	173,514				140,703				173,514	140,703
Deferred income taxes	39,308				53,933				39,308	53,933
Total assets	475,531				407,153				475,531	407,153
Retained earnings	220,307				236,993				220,307	236,993
Accumulated other comprehensive loss	(62,039)				(61,493)				(62,039)	(61,493)
Total stockholders’ equity	229,055				229,552				229,055	229,552	$ 197,317	$ 120,466
Total liabilities and stockholders’ equity	475,531				407,153				475,531	407,153
Cost of goods sold	96,939	$ 105,716	$ 111,175	$ 85,672	91,025	$ 88,305	$ 89,531	$ 85,761	399,502	354,622	373,214
Gross profit	52,599	52,211	56,191	46,041	42,775	49,882	49,494	44,727	207,042	186,878	171,168
Selling expenses	41,256	38,041	42,414	32,828	33,230	34,388	32,408	33,303	154,539	133,329	123,260
Operating expenses									205,918	147,700	173,358
Income (loss) from operations	2,001	(2,767)	28	1,862	(3,096)	4,109	36,997	1,168	1,124	39,178	(2,190)
Income (loss) before taxes									(968)	37,366	(448)
Income tax expense (benefit)									17,312	14,815	(72,239)
Net (loss) income	$ 133	$ (2,193)	$ (17,060)	$ 840	$ (1,837)	$ 2,846	$ 20,728	$ 814	$ (18,280)	$ 22,551	$ 71,791
Net income available to common stockholders per common share—basic (in US$ per share)	$ 0.00	$ (0.14)	$ (1.03)	$ 0.05	$ (0.11)	$ 0.17	$ 1.25	$ 0.05	$ (1.11)	$ 1.35	$ 4.35
Net income available to common stockholders per common share—diluted (in US$ per share)	$ 0.00	$ (0.14)	$ (1.03)	$ 0.05	$ (0.11)	$ 0.17	$ 1.24	$ 0.05	$ (1.11)	$ 1.34	$ 4.32
Net income	$ 133	$ (2,193)	$ (17,060)	$ 840	$ (1,837)	$ 2,846	$ 20,728	$ 814	$ (18,280)	$ 22,551	$ 71,791
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Deferred income taxes									17,154	14,343	(72,556)
Net losses (gains) on derivative instruments and investments									1,982	2,361	16,536
Change in operating assets and liabilities:
Inventories									(15,513)	(8,041)	10,063
Derivative assets (liabilities), net									(7,782)	2,264	(10,295)
Net cash provided by operating activities									$ 8,855	42,112	27,628
As Previously Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Inventories					56,251					56,251
Total assets					117,164					117,164
Deferred income taxes					63,055					63,055
Total assets					392,736					392,736
Retained earnings					221,182					221,182
Accumulated other comprehensive loss					(60,099)					(60,099)
Total stockholders’ equity					215,135					215,135
Total liabilities and stockholders’ equity					392,736					392,736
Cost of goods sold										327,765	335,907
Gross profit										213,735	208,475
Selling expenses										157,198	150,198
Operating expenses										171,569	200,296
Income (loss) from operations										42,166	8,179
Income (loss) before taxes										40,354	9,921
Income tax expense (benefit)										15,954	(79,997)
Net (loss) income										$ 24,400	$ 89,918
Net income available to common stockholders per common share—basic (in US$ per share)										$ 1.46	$ 5.45
Net income available to common stockholders per common share—diluted (in US$ per share)										$ 1.45	$ 5.41
Net income										$ 24,400	$ 89,918
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Deferred income taxes										15,482	(80,314)
Net losses (gains) on derivative instruments and investments										(205)	12,910
Change in operating assets and liabilities:
Inventories										(8,504)	3,608
Derivative assets (liabilities), net										2,305	(10,583)
Net cash provided by operating activities										42,112	27,628
Restatement Adjustment | LIFO to FIFO Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Inventories					19,675					19,675
Total assets					19,675					19,675
Deferred income taxes					(7,625)					(7,625)
Total assets					12,050					12,050
Retained earnings					13,444					13,444
Accumulated other comprehensive loss					(1,394)					(1,394)
Total stockholders’ equity					12,050					12,050
Total liabilities and stockholders’ equity					12,050					12,050
Cost of goods sold										1,739	8,593
Gross profit										(1,739)	(8,593)
Selling expenses										0	0
Operating expenses										0	0
Income (loss) from operations										(1,739)	(8,593)
Income (loss) before taxes										(1,739)	(8,593)
Income tax expense (benefit)										(663)	6,430
Net (loss) income										$ (1,076)	$ (15,023)
Net income available to common stockholders per common share—basic (in US$ per share)										$ (0.07)	$ (0.91)
Net income available to common stockholders per common share—diluted (in US$ per share)										$ (0.07)	$ (0.90)
Net income										$ (1,076)	$ (15,023)
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Deferred income taxes										(663)	6,430
Net losses (gains) on derivative instruments and investments										2,566	3,626
Change in operating assets and liabilities:
Inventories										(786)	4,677
Derivative assets (liabilities), net										(41)	288
Net cash provided by operating activities										0	(2)
Restatement Adjustment | Preferable Freight and Warehousing Adjustments
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Inventories					3,821					3,821
Total assets					3,821					3,821
Deferred income taxes					(1,480)					(1,480)
Total assets					2,341					2,341
Retained earnings					2,341					2,341
Accumulated other comprehensive loss					0					0
Total stockholders’ equity					2,341					2,341
Total liabilities and stockholders’ equity					2,341					2,341
Cost of goods sold										19,835	21,104
Gross profit										(19,835)	(21,104)
Selling expenses										(19,241)	(20,502)
Operating expenses										(19,241)	(20,502)
Income (loss) from operations										(594)	(602)
Income (loss) before taxes										(594)	(602)
Income tax expense (benefit)										(226)	450
Net (loss) income										$ (368)	$ (1,052)
Net income available to common stockholders per common share—basic (in US$ per share)										$ (0.02)	$ (0.07)
Net income available to common stockholders per common share—diluted (in US$ per share)										$ (0.02)	$ (0.07)
Net income										$ (368)	$ (1,052)
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Deferred income taxes										(226)	450
Net losses (gains) on derivative instruments and investments										0	0
Change in operating assets and liabilities:
Inventories										594	604
Derivative assets (liabilities), net										0	0
Net cash provided by operating activities										0	2
Restatement Adjustment | Corrections of Freight, Overhead Variances and PPVs
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Inventories					43					43
Total assets					43					43
Deferred income taxes					(17)					(17)
Total assets					26					26
Retained earnings					26					26
Accumulated other comprehensive loss					0					0
Total stockholders’ equity					26					26
Total liabilities and stockholders’ equity					$ 26					26
Cost of goods sold										5,283	7,610
Gross profit										(5,283)	(7,610)
Selling expenses										(4,628)	(6,436)
Operating expenses										(4,628)	(6,436)
Income (loss) from operations										(655)	(1,174)
Income (loss) before taxes										(655)	(1,174)
Income tax expense (benefit)										(250)	878
Net (loss) income										$ (405)	$ (2,052)
Net income available to common stockholders per common share—basic (in US$ per share)										$ (0.02)	$ (0.12)
Net income available to common stockholders per common share—diluted (in US$ per share)										$ (0.02)	$ (0.12)
Net income										$ (405)	$ (2,052)
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Deferred income taxes										(250)	878
Net losses (gains) on derivative instruments and investments										0	0
Change in operating assets and liabilities:
Inventories										655	1,174
Derivative assets (liabilities), net										0	0
Net cash provided by operating activities										$ 0	$ 0