Real Estate Investments and Related Intangibles - Intangible Lease Assets and Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Intangible lease assets:
Intangible lease assets, net	$ 938,157		$ 938,157		$ 1,037,487
Intangible lease liabilities:
Weighted-Average Useful Life			19 years 7 months 6 days
Intangible lease liabilities, net	124,009		$ 124,009		143,583
Accumulated amortization	103,156		103,156		99,315
Amortization expense	393	$ 692	$ 1,929	$ 2,034
In-place leases and other intangible assets [Member]
Intangible lease assets:
Weighted-Average Useful Life			16 years 3 months 18 days
Intangible lease assets, net	755,914		$ 755,914		854,196
Accumulated amortization	802,778		$ 802,778		748,689
Leasing commissions [Member]
Intangible lease assets:
Weighted-Average Useful Life			9 years 3 months 18 days
Intangible lease assets, net	17,221		$ 17,221		17,808
Accumulated amortization	7,011		$ 7,011		6,027
Above-market lease assets and deferred lease incentives [Member]
Intangible lease assets:
Weighted-Average Useful Life			16 years 10 months 24 days
Intangible lease assets, net	165,022		$ 165,022		165,483
Accumulated amortization	$ 124,953		124,953		$ 112,438
Above‑ And Below-Market Leases and Deferred Lease Incentives [Member]
Intangible lease liabilities:
Amortization expense			1,900	2,000
In-Place Leases, Leasing Commissions and Other Lease Intangibles [Member]
Intangible lease liabilities:
Amortization expense			$ 103,500	$ 96,900