Consolidated Debt Obligations Abstract.

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Secured debt net of premiums discount.

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Total unsecured indebtedness.

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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

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Amount, after accumulated amortization, of debt discount (premium).

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Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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DEBT OBLIGATIONS - Consolidated Debt Obligations Outstanding (Details) - USD ($) $ in Thousands			12 Months Ended
	Dec. 13, 2018	Dec. 12, 2018	Dec. 31, 2019	Dec. 31, 2018
Consolidated debt obligations
Plus: premiums/(discounts), net			$ 10,707
Net deferred financing costs			(10,336)
Total Debt Obligations			2,144,418	$ 2,028,046
Secured Debt
Consolidated debt obligations
Long-term debt, gross			315,437	323,032
Plus: premiums/(discounts), net			(1,383)	(1,759)
Net deferred financing costs			(242)	(404)
Total mortgage indebtedness			313,812	320,869
Secured Debt \| Two Logan Square
Consolidated debt obligations
Long-term debt, gross			$ 81,103	82,805
Effective interest rate			3.98%
Secured Debt \| Four Tower Bridge
Consolidated debt obligations
Long-term debt, gross			$ 9,291	9,526
Effective interest rate			4.50%
Secured Debt \| One Commerce Square
Consolidated debt obligations
Long-term debt, gross			$ 116,571	120,183
Effective interest rate			3.64%
Secured Debt \| Two Commerce Square
Consolidated debt obligations
Long-term debt, gross			$ 108,472	110,518
Effective interest rate			4.51%
Unsecured Debt
Consolidated debt obligations
Long-term debt, gross			$ 1,828,610	1,721,110
Plus: premiums/(discounts), net			12,090	(4,096)
Net deferred financing costs			(10,094)	(9,837)
Total unsecured indebtedness			1,830,606	1,707,177
Unsecured Debt \| $600 million Unsecured Credit Facility
Consolidated debt obligations
Long-term debt, gross			0	92,500
Unsecured Debt \| Seven-Year Term Loan - Swapped to fixed
Consolidated debt obligations
Long-term debt, gross	$ 250,000		$ 250,000	250,000
Effective interest rate	2.87%		2.87%
Unsecured Debt \| $350.0M 3.95% Guaranteed Notes due 2023
Consolidated debt obligations
Long-term debt, gross			$ 350,000	350,000
Effective interest rate			3.87%
Unsecured Debt \| $350.0M 4.10% Guaranteed Notes due 2024
Consolidated debt obligations
Long-term debt, gross			$ 350,000	250,000
Effective interest rate			3.78%
Unsecured Debt \| $450.0M 3.95% Guaranteed Notes due 2027
Consolidated debt obligations
Long-term debt, gross			$ 450,000	450,000
Effective interest rate			4.03%
Unsecured Debt \| $350.0M 4.55% Guaranteed Notes due 2029
Consolidated debt obligations
Long-term debt, gross			$ 350,000	250,000
Effective interest rate			4.30%
Unsecured Debt \| Indenture IA (Preferred Trust I)
Consolidated debt obligations
Long-term debt, gross			$ 27,062	27,062
Unsecured Debt \| Indenture IB (Preferred Trust I) - Swapped to fixed
Consolidated debt obligations
Long-term debt, gross			$ 25,774	25,774
Effective interest rate			3.30%
Unsecured Debt \| Indenture II (Preferred Trust II)
Consolidated debt obligations
Long-term debt, gross			$ 25,774	$ 25,774
LIBOR \| Unsecured Debt \| $600 million Unsecured Credit Facility
Consolidated debt obligations
Variable interest rate			1.10%
LIBOR \| Unsecured Debt \| Seven-Year Term Loan - Swapped to fixed
Consolidated debt obligations
Variable interest rate	1.25%	1.80%
LIBOR \| Unsecured Debt \| Indenture IA (Preferred Trust I)
Consolidated debt obligations
Variable interest rate			1.25%
LIBOR \| Unsecured Debt \| Indenture II (Preferred Trust II)
Consolidated debt obligations
Variable interest rate			1.25%