Derivative Financial Instruments (Details) - Jun. 30, 2015	USD ($)	USD ($) swap_agreement
Derivative [Line Items]
Number of forward starting swaps | swap_agreement		4
Interest rate cash flow hedge gain (loss) to be reclassified to interest expense during the next 12 months	$ (200,000)	$ (200,000)
Interest Rate Swap [Member]
Derivative [Line Items]
Loss on forward starting interest rate swap agreements recognized in OCI	(961,000)	(1,684,000)
Cash Flow Hedging [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Notional value	225,000,000.0	225,000,000.0
Interest Expense [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Amount of loss reclassified from accumulated OCI into Income (effective portion)	(31,000)	(31,000)
Amount of gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)	$ 0	$ 0