| Derivative Instruments and Hedging Activities  - Derivative Activity in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands | 12 Months Ended | |
|---|---|---|
| Jun. 30, 2017 | Jun. 30, 2016 | |
| Accumulated Other Comprehensive Income [Roll Forward] | ||
| Beginning balance | $ 1,210 | $ 7,110 | 
| Amount reclassified to income | (3,222) | 3,722 | 
| Net change in unrealized gains or losses | 10,138 | (9,622) | 
| Ending balance | $ 8,126 | $ 1,210 | 
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- Definition Accumulated Other Comprehensive Income [Roll Forward] No definition available. 
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- Definition Amount before tax of increase (decrease) in accumulated equity from transactions and other events and circumstances from non-owner sources, including portion attributable to noncontrolling interest. Excludes net income (loss), and accumulated changes in equity from transactions resulting from investments by owners (distributions to owners). No definition available. 
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- Definition The effective portion of net gain (loss) reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition The effective portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments that was recognized in other comprehensive income during the current period. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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