Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Commercial real estate properties, at cost:
Land	$ 201,196	$ 201,196
Development costs	9,325	7,989
Building and improvements	2,914,528	2,900,248
Commercial real estate properties, at cost	3,125,049	3,109,433
Less: accumulated depreciation	(911,546)	(862,534)
Commercial real estate properties, net	2,213,503	2,246,899
Cash and cash equivalents	872,970	233,946
Restricted cash	58,878	37,651
Tenant and other receivables	29,800	25,423
Deferred rent receivables	226,444	220,960
Prepaid expenses and other assets	68,109	65,453
Deferred costs, net	211,356	228,150
Acquired below-market ground leases, net	348,651	352,566
Right of use assets	29,205	29,307
Goodwill	491,479	491,479
Total assets	4,550,395	3,931,834
Liabilities:
Mortgage notes payable, net	603,974	605,542
Senior unsecured notes, net	973,053	798,392
Unsecured term loan facilities, net	387,059	264,640
Unsecured revolving credit facility, net	546,778	0
Accounts payable and accrued expenses	104,992	143,786
Acquired below-market leases, net	35,170	39,679
Ground lease liabilities	29,205	29,307
Deferred revenue and other liabilities	62,996	72,015
Tenants’ security deposits	51,130	30,560
Total liabilities	2,794,357	1,983,921
Commitments and contingencies
Capital:
Total capital	1,756,038	1,947,913
Total liabilities and capital	4,550,395	3,931,834
Private Perpetual Preferred Units, Series 2019
Capital:
Private perpetual preferred units	21,936	21,147
Private Perpetual Preferred Units, Series 2014
Capital:
Private perpetual preferred units	8,004	8,004
Series PR Operating Partnership Units
Capital:
ESRT partner's capital (2,908,226 and 2,996,520 general partner operating partnership units and 170,438,353 and 178,897,876 limited partner operating partnership units outstanding in 2020 and 2019, respectively)	1,080,221	1,228,520
Limited partner operating partnership units	647,520	680,580
Series ES operating partnership units
Capital:
Limited partner operating partnership units	(770)	7,262
Series 60 operating partnership units
Capital:
Limited partner operating partnership units	(588)	1,593
Series 250 operating partnership units
Capital:
Limited partner operating partnership units	$ (285)	$ 807