Notes Payable (NAB Australian Corporate Term Loan) (Narrative) (Details)	0 Months Ended				12 Months Ended				1 Months Ended						0 Months Ended						12 Months Ended
	Jun. 24, 2011 BOSI Australia Corporate Credit Facility [Member] USD ($)	Jun. 24, 2011 BOSI Australia Corporate Credit Facility [Member] AUD	Dec. 31, 2010 BOSI Australia Corporate Credit Facility [Member] USD ($)	Dec. 31, 2010 BOSI Australia Corporate Credit Facility [Member] AUD	Dec. 31, 2012 NAB Australian Corporate Credit Facility [Member] USD ($)	Dec. 31, 2012 NAB Australian Corporate Credit Facility [Member] AUD	Jun. 24, 2011 NAB Australian Corporate Credit Facility [Member] USD ($)	Jun. 24, 2011 NAB Australian Corporate Credit Facility [Member] AUD	Dec. 31, 2012 NAB Australian Corporate Term Loan [Member] USD ($)	Dec. 31, 2012 NAB Australian Corporate Term Loan [Member] AUD	Jun. 24, 2011 NAB Australian Corporate Term Loan [Member] USD ($)	Jun. 24, 2011 NAB Australian Corporate Term Loan [Member] AUD	Jun. 24, 2011 NAB Australian Corporate Line Of Credit [Member] USD ($)	Jun. 24, 2011 NAB Australian Corporate Line Of Credit [Member] AUD	Aug. 02, 2011 NAB Australian Corporate Revolver [Member] USD ($)	Aug. 02, 2011 NAB Australian Corporate Revolver [Member] AUD	Dec. 31, 2012 NAB Australian Corporate Revolver [Member] USD ($)	Dec. 31, 2012 NAB Australian Corporate Revolver [Member] AUD	Dec. 31, 2012 NAB Guarantee Facility [Member] USD ($)	Dec. 31, 2012 NAB Guarantee Facility [Member] AUD	Dec. 31, 2012 Minimum [Member] NAB Australian Corporate Credit Facility [Member] USD ($)	Dec. 31, 2012 Minimum [Member] NAB Australian Corporate Credit Facility [Member] AUD	Dec. 31, 2012 Maximum [Member] NAB Australian Corporate Credit Facility [Member] USD ($)	Dec. 31, 2012 Maximum [Member] NAB Australian Corporate Credit Facility [Member] AUD
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 115,800,000	110,000,000					$ 110,500,000	105,000,000			$ 94,700,000	90,000,000	$ 9,500,000	9,000,000			$ 10,400,000	10,000,000	$ 5,200,000	5,000,000
Repayment of debt	1,600,000	1,500,000							6,300,000	6,000,000					9,700,000	9,000,000
Line of credit facility, amount outstanding	105,800,000	100,500,000	101,700,000	100,500,000					75,300,000	72,500,000					0
Line of credit facility, term					3 years	3 years
Spread on variable interest rate																					2.15%	2.15%	2.90%	2.90%
Annual principal payment																					7,300,000	7,000,000	9,400,000	9,000,000
Line of credit facility, maximum amount transferable outside of Australia					$ 4,200,000	4,000,000
Interest rate swap term					5 years	5 years
Percentage of variable interest debt converted to fixed rate					100.00%	100.00%
Swap contract rate					5.50%	5.50%