2. Significant Accounting Policies Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Significant Accounting Policies [Line Items]
Cash at Bank Held by Parent Company not Part of Operating Partnership	$ 4,200
Capitalized Interest and Deferred Financing Cost Amortization	11,000	$ 12,300	$ 10,200
Capitalized Internal Leasing And Development Costs	8,000	7,500	4,500
Depreciation	103,500	98,800	92,300
Asset Impairment Charges	0	122,500	0
Gain (Loss) on Disposition of Property Plant Equipment	22,833	0	0
Loss on early extinguishment of debt	(1,232)	0	(1,701)
Write off of Deferred Debt Issuance Cost	1,232	0	1,701
Write off of Unamortized Leasing Costs		700
Amortization of Deferred Leasing Fees	4,200	4,900	4,100
Fuel Inventory	4,200	4,500
Write Off of Unreserved Straight-Line Rents Receivable		400
Write off of Unamortized Lease Inducements		100
Write off of Unamortized Lease Intangibles		1,000
Notes Receivable, Gross	25,000	6,500
Account receivable reserve	23,600	5,100
Notes Receivable, Net	1,400	1,400
DeferredRentReceivablesAllowance	0	100
Income Tax Expense (Benefit)	100	0	100
Deferred Income Tax Expense (Benefit)		(200)
Deferred Tax Assets, Gross	200	4,600
Deferred Tax Liabilities, Gross	0	2,300
Deferred Tax Assets, Net	200	2,300
Operating Loss Carryforwards	200
Allocated Share-based Compensation Expense	6,600	5,300	6,200
Employee Service Share-based Compensation, Allocation of Recognized Period Costs, Capitalized Amount	900	800	700
Foreign Currency Transaction Gain (Loss), before Tax	100
Retained Earnings (Accumulated Deficit)	$ 0	$ (79,945)
Building and Building Improvements [Member]
Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life	40 years
Minimum [Member] | Building and Building Improvements [Member]
Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life	10 years
Minimum [Member] | Personal Property [Member]
Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life	3 years
Maximum [Member] | Building and Building Improvements [Member]
Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life	40 years
Maximum [Member] | Personal Property [Member]
Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life	7 years
Revolving Credit Facility [Member]
Significant Accounting Policies [Line Items]
Loss on early extinguishment of debt	$ 1,232
Write off of Deferred Debt Issuance Cost	$ 500		300
Unsecured Term Loan [Member]
Significant Accounting Policies [Line Items]
Loss on early extinguishment of debt			1,400
Write off of Deferred Debt Issuance Cost			$ 700