Summary of Significant Accounting Policies - Corrections to Consolidated Statements of Cash Flows (Details) (USD $)	9 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Net income (loss)	$ 9,021,000	$ (5,484,000)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	21,335,000	24,778,000
Provision for (recovery of) doubtful accounts	78,000	(890,000)
Deferred income taxes	110,000	111,000
Net gains on sales of assets	(13,000)	(4,388,000)
ESOP and share-based compensation expense	3,415,000	2,639,000
Net losses on derivatives and investments	4,235,000	9,315,000
Change in operating assets and liabilities:
Restricted cash	8,084,000	(2,140,000)
Purchases of trading securities held for investment	(4,456,000)	(6,408,000)
Proceeds from sales of trading securities held for investment	3,443,000	5,452,000
Short-term investments		0
Accounts and notes receivable	(818,000)	(1,167,000)
Inventories	(10,397,000)	(1,291,000)
Income tax receivable	234,000	645,000
Prepaid expenses and other assets	309,000	522,000
Accounts payable	6,665,000	3,737,000
Accrued payroll expenses and other current liabilities	(51,000)	(6,657,000)
Accrued postretirement benefits	(1,028,000)	462,000
Other long-term liabilities	747,000	(1,416,000)
Net cash provided by operating activities	33,854,000	17,820,000
Previously Reported
Increase (decrease) in derivative liabilities		9,400,000
Net income (loss)		(5,484,000)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization		24,778,000
Provision for (recovery of) doubtful accounts		(890,000)
Deferred income taxes		111,000
Net gains on sales of assets		(4,388,000)
ESOP and share-based compensation expense		2,639,000
Net losses on derivatives and investments		9,315,000
Change in operating assets and liabilities:
Restricted cash		(2,140,000)
Purchases of trading securities held for investment		0
Proceeds from sales of trading securities held for investment		0
Short-term investments		(10,347,000)
Accounts and notes receivable		(1,167,000)
Inventories		(1,291,000)
Income tax receivable		645,000
Prepaid expenses and other assets		522,000
Accounts payable		3,737,000
Accrued payroll expenses and other current liabilities		2,734,000
Accrued postretirement benefits		462,000
Other long-term liabilities		(1,416,000)
Net cash provided by operating activities		17,820,000
Adjustments
Net income (loss)		0
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization		0
Provision for (recovery of) doubtful accounts		0
Deferred income taxes		0
Net gains on sales of assets		0
ESOP and share-based compensation expense		0
Net losses on derivatives and investments		0
Change in operating assets and liabilities:
Restricted cash		0
Purchases of trading securities held for investment		(6,408,000)
Proceeds from sales of trading securities held for investment		5,452,000
Short-term investments		10,347,000
Accounts and notes receivable		0
Inventories		0
Income tax receivable		0
Prepaid expenses and other assets		0
Accounts payable		0
Accrued payroll expenses and other current liabilities		(9,391,000)
Accrued postretirement benefits		0
Other long-term liabilities		0
Net cash provided by operating activities		$ 0