Real Estate Investments and Related Intangibles - Schedule of Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Acquisition, 2019 [Member]
Real estate investments, at cost:
Land	$ 83,476	$ 86,285	$ 110,634
Buildings, fixtures and improvements	268,470	350,942	523,445
Total tangible assets	351,946	437,227	634,079
Acquired intangible assets:
Total purchase price of assets acquired	403,573	502,652	748,784
Acquisition, 2019 [Member] | In-place leases and other intangible assets [Member]
Acquired intangible assets:
Acquired intangible assets	$ 51,627	62,791	105,940
Weighted-average useful life	16 years 6 months
Acquisition, 2019 [Member] | Above-market leases [Member]
Acquired intangible assets:
Acquired intangible assets	$ 0	2,750	10,445
Acquisition, 2019 [Member] | Below Market Lease [Member]
Acquired intangible assets:
Assumed intangible liabilities, Below-market leases	$ 0	(116)	(1,680)
Acquisitions 2018 [Member]
Acquired intangible assets:
Total purchase price of assets acquired		$ 502,700
Acquisitions 2018 [Member] | In-place leases and other intangible assets [Member]
Acquired intangible assets:
Weighted-average useful life		16 years 3 months 18 days
Acquisitions 2018 [Member] | Above-market leases [Member]
Acquired intangible assets:
Weighted-average useful life		10 years 9 months 18 days
Acquisitions 2018 [Member] | Below Market Lease [Member]
Acquired intangible assets:
Weighted-average useful life		9 years 10 months 24 days
Acquisitions, 2017 [Member]
Acquired intangible assets:
Total purchase price of assets acquired			$ 748,800
Acquisitions, 2017 [Member] | In-place leases and other intangible assets [Member]
Acquired intangible assets:
Weighted-average useful life			15 years 9 months 18 days
Acquisitions, 2017 [Member] | Above-market leases [Member]
Acquired intangible assets:
Weighted-average useful life			18 years
Acquisitions, 2017 [Member] | Below Market Lease [Member]
Acquired intangible assets:
Weighted-average useful life			13 years 9 months 18 days