Derivatives (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012 derivatives	Sep. 30, 2011
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Fair value of interest rate hedges recognized in other comprehensive income	$ 5,753
Interest rate hedges gain reclassified as and increase and as a (reduction) to interest expense	171	(47)
Interest rate hedges gain (loss) to be reclassified into interest expense over next 12 months	$ 244
Number of interest rate derivatives held	0