Fair Value of Financial Instruments - Summary of financial assets and liabilities measured at fair value on a recurring basis and fair value hierarchy (Details) (Fair Value, Measurements, Recurring, Other long-term liabilities, Level 2, Interest Rate Swap Agreements, USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Jun. 30, 2014
Fair Value, Measurements, Recurring \| Other long-term liabilities \| Level 2 \| Interest Rate Swap Agreements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swap agreements	$ 9,122	$ 7,774

Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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