Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2021

Accounting Policies [Abstract]

Schedule of estimated useful lives

Properties other than Right of use assets - operating leases are depreciated using the straight-line method over the estimated useful lives of the assets. The estimated useful lives are as follows:

Category	Term
Building (fee ownership)	40 years
Building improvements	shorter of remaining life of the building or useful life
Building (leasehold interest)	lesser of 40 years or remaining term of the lease
Right of use assets - financing leases	lesser of 40 years or remaining lease term
Furniture and fixtures	4 to 7 years
Tenant improvements	shorter of remaining term of the lease or useful life

Summary of identified intangible assets (acquired above-market leases and in-place leases) and intangible liabilities (acquired below-market leases)

The following summarizes our identified intangible assets (acquired above-market leases and in-place leases) and intangible liabilities (acquired below-market leases) as of December 31, 2021 and 2020 (in thousands):

	December 31,
	2021		2020
Identified intangible assets (included in other assets):
Gross amount	$	199,722	$	215,673
Accumulated amortization	(182,643)		(190,523)
Net (1)	$	17,079	$	25,150
Identified intangible liabilities (included in deferred revenue):
Gross amount	$	212,767	$	241,409
Accumulated amortization	(210,262)		(230,479)
Net (1)	$	2,505	$	10,930

(1)    As of December 31, 2021, $1.8 million of net intangible assets and no net intangible liabilities were reclassified to assets held for sale and liabilities related to assets held for sale. As of December 31, 2020, no net intangible assets and no net intangible liabilities were reclassified to assets held for sale and liabilities related to assets held for sale.

Schedule of estimated annual amortization of acquired above-market leases, net of acquired below-market leases

The estimated annual amortization of acquired above-market leases, net of acquired (below-market) leases (a component of rental revenue), for each of the five succeeding years is as follows (in thousands):    

2022	505
2023	476
2024	56
2025	234
2026	205

Schedule of estimated annual amortization of all other identifiable assets

The estimated annual amortization of all other identifiable assets (a component of depreciation and amortization expense) including tenant improvements for each of the five succeeding years is as follows (in thousands):

2022	5,575
2023	5,409
2024	3,544
2025	2,027
2026	1,850

Schedule of marketable securities

As of December 31, 2021 and 2020, we held the following marketable securities (in thousands):

	December 31,
	2021		2020
Commercial mortgage-backed securities	$	24,146	$	28,570
Total marketable securities available-for-sale	$	24,146	$	28,570
Equity marketable securities	$	10,606	$	—
Total investment in marketable securities	$	34,752	$	28,570

Schedules of concentration of risk, by risk factor

For the years ended December 31, 2021, 2020, and 2019, the following properties contributed more than 5.0% of our annualized cash rent from office properties, including our share of annualized cash rent from joint venture office properties:

Property	2021	Property	2020	Property	2019
11 Madison Avenue	10.8%	11 Madison Avenue	8.2%	1185 Avenue of the Americas	7.6%
420 Lexington Avenue	8.3%	420 Lexington Avenue	7.5%	11 Madison Avenue	7.4%
1515 Broadway	8.1%	1185 Avenue of the Americas	6.9%	420 Lexington Avenue	6.6%
1185 Avenue of the Americas	8.0%	1515 Broadway	6.6%	1515 Broadway	6.1%
280 Park Avenue	6.7%	220 East 42nd Street	5.9%	One Madison Avenue	6.0%
919 Third Avenue	5.3%	280 Park Ave	5.4%	220 East 42nd Street	5.5%
485 Lexington Avenue	5.3%
555 West 57th Street	5.2%