Summary of Significant Accounting Policies: (Details 4)	12 Months Ended
	Dec. 31, 2012 item
Segment Information:
Number of business segments	1
Number of geographic areas in which the Company operates	1
Minimum
Deferred Charges:
Deferred lease costs, amortization period	1 year
Deferred financing costs, amortization period	1 year
Leasing commissions and legal costs, amortization period	5 years
Maximum
Deferred Charges:
Deferred lease costs, amortization period	15 years
Deferred financing costs, amortization period	15 years
Leasing commissions and legal costs, amortization period	10 years