Derivative Instruments and Hedging Activities Effect of Derivative Financial Instruments on the Statements of Income and Comprehensive Income (Details) (USD $)	6 Months Ended		3 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014 Cash Flow Hedging [Member] Interest Rate Swap [Member]	Jun. 30, 2013 Cash Flow Hedging [Member] Interest Rate Swap [Member]	Jun. 30, 2014 Cash Flow Hedging [Member] Interest Rate Swap [Member] Interest Expense [Member]	Jun. 30, 2013 Cash Flow Hedging [Member] Interest Rate Swap [Member] Interest Expense [Member]	Jun. 30, 2014 Cash Flow Hedging [Member] Interest Rate Swap [Member] Other Expense [Member]	Jun. 30, 2013 Cash Flow Hedging [Member] Interest Rate Swap [Member] Other Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain/(loss) recognized in OCI on derivative	$ (1,439,000)	$ 2,221,000	$ (1,032,000)	$ 2,333,000
Amount of loss reclassified from accumulated OCI into interest expense	(693,000)	(89,000)			(349,000)	0
Amount of gain/(loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)	$ 0	$ 0					$ 0	$ 0