Derivative Instruments (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Derivative Instruments [Line Items]
Increase (decrease) in interest expense from derivatives	$ 1,800,000	$ 1,500,000	$ 1,500,000	$ 1,700,000
Interest rate swap	6,219,000		6,219,000		4,722,000
Interest Rate Swap [Member]
Derivative Instruments [Line Items]
Interest rate swap	$ 6,200,000		$ 6,200,000		$ 4,700,000
NAB Australian Corporate Credit Facility [Member]
Derivative Instruments [Line Items]
Minimum swap percentage			75.00%
Terms of agreement in interest rate swap, years			5
Percentage of variable interest debt converted to fixed rate			100.00%
Pay Fixed Rate			5.50%
US GE Capital Term Loan [Member]
Derivative Instruments [Line Items]
Minimum swap percentage			50.00%
Minimum years for drawdowns on swap			3
Percentage of variable interest debt converted to fixed rate			100.00%
Pay Fixed Rate			1.34%