Schedule III - Real Estate and Accumulated Depreciation Schedule III - Real Estate and Accumulated Depreciation (Summary) (Details) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate, Gross, January 1	$ 3,074,846	$ 2,818,365	$ 2,665,903
Payments to Acquire Property, Plant, and Equipment	116,724	237,186	147,645
Change In Accounts Payable, Real Property Additions	(784)	1,829	1,689
Additions Through Contingent Liabilities	348	292	171
Additions Through Assumption Of Debt		0	0
Change in Straight-line Rent Receivable, Investments in Real Estate	0	38,000	0
Payments for Delayed Tax Exempt Exchange	0	0	3,775
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Other Deduction	0	0	(818)
Settlement of Contingent Asset Acquisition Liability	0	0	(750)
Settlement Of Mortgage Note By Real Estate Acquisition	63,220	14,000	0
Additions Through Settlement Of Mortgage Note	63,220	14,000	0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Cost of Investment in Real Estate Sold	(62)	0	0
SEC Schedule III, Real Estate, Gross, December 31	3,265,070	3,074,846	2,818,365
SEC Schedule III, Real Estate Accumulated Depreciation, January 1	514,453	451,483	380,202
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation, Depreciation Expense	83,150	76,816	71,349
Finance Lease, Right-of-Use Asset, Amortization	0	60	0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation, Investment in Real Estate Sold	(35)	0	0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation, Other Deduction	0	(13,906)	0
SEC Schedule III, Real Estate Accumulated Depreciation, December 31	597,638	514,453	451,483
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation, Other Addition	0	0	(68)
Inventory, Real Estate, Held-for-sale	$ 0	$ (34,826)	$ 0