Debt Interest Rate Swaps (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Derivative [Line Items]
Incremental interest expense arising from difference between interest paid and interest received related to swap agreements	$ 1,433,000	$ 1,379,000	$ 1,300,000
Interest Rate Swap 1, Credit Facility [Member]
Derivative [Line Items]
Interest rate swap agreement, termination date	Oct. 19, 2016
Interest rate swap agreement, fixed interest rate	1.185%
Interest rate swap agreement, effective date	Nov. 21, 2011
Interest rate swap agreement, notional amount	25,000,000
Interest Rate Swap 2, Credit Facility [Member]
Derivative [Line Items]
Interest rate swap agreement, termination date	Oct. 19, 2016
Interest rate swap agreement, fixed interest rate	1.185%
Interest rate swap agreement, effective date	Nov. 21, 2011
Interest rate swap agreement, notional amount	25,000,000
Interest Rate Swap 3, Credit Facility Member
Derivative [Line Items]
Interest rate swap agreement, termination date	Oct. 19, 2016
Interest rate swap agreement, fixed interest rate	1.10%
Interest rate swap agreement, effective date	Dec. 21, 2011
Interest rate swap agreement, notional amount	50,000,000
Interest Rate Swap 4, Credit Facility [Member]
Derivative [Line Items]
Interest rate swap agreement, termination date	Oct. 19, 2016
Interest rate swap agreement, fixed interest rate	1.05%
Interest rate swap agreement, effective date	Jan. 17, 2012
Interest rate swap agreement, notional amount	25,000,000
Interest Rate Swap 5, Credit Facility [Member]
Derivative [Line Items]
Interest rate swap agreement, termination date	Oct. 19, 2016
Interest rate swap agreement, fixed interest rate	0.99%
Interest rate swap agreement, effective date	Jan. 19, 2012
Interest rate swap agreement, notional amount	$ 25,000,000
London Interbank Offered Rate (LIBOR) [Member]
Derivative [Line Items]
Debt Instrument, Interest Rate Margins on Variable Rates, Minimum	1.15%
Debt Instrument, Interest Rate Margins on Variable Rate, Maximum	1.65%