Investments and Derivative Instruments - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) (Fair Value, Measurements, Recurring, USD $) In Thousands, unless otherwise specified	Mar. 31, 2013		Jun. 30, 2012
Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Futures, options and other derivative assets			$ 1,626	[1]
Derivative liabilities	5,930	[2]	410	[3]
Derivative liabilities - interest rate swap	35
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Futures, options and other derivative assets			0	[1]
Derivative liabilities	0	[2]	0	[3]
Derivative liabilities - interest rate swap	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Futures, options and other derivative assets			1,626	[1]
Derivative liabilities	5,930	[2]	410	[3]
Derivative liabilities - interest rate swap	35
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Futures, options and other derivative assets			0	[1]
Derivative liabilities	0	[2]	0	[3]
Derivative liabilities - interest rate swap	0
Preferred Stock | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred stock	20,769	[1]	19,395	[1]
Preferred Stock | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred stock	16,454	[1]	14,078	[1]
Preferred Stock | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred stock	4,315	[1]	5,317	[1]
Preferred Stock | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred stock	$ 0	[1]	$ 0	[1]

[1] Included in "Short-term investments" on the consolidated balance sheets.

[2] Included in "Other current liabilities" on the consolidated balance sheet.

[3] Included in "Accounts Payable" on the consolidated balance sheet.