Derivative Financial Instruments (Details) (USD $)	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Derivative [Line Items]
Interest rate swaps designated as cash flow hedges, notional amount	$ 10,000,000	$ 10,000,000
Fair values of effective portion of hedges reflected in Other Comprehensive Income	(802,000)	(1,060,000)
Interest rate derivatives, combined notional amount	73,970,000	28,630,000
Swap [Member]
Derivative [Line Items]
Number of interest rate derivative positions	8	2
Additional [Member]
Derivative [Line Items]
Interest rate derivatives, combined notional amount	$ 7,350,000
Additional [Member] | Swap [Member]
Derivative [Line Items]
Number of interest rate derivative positions	1