Goodwill and Other Intangibles - Intangible Assets and Liabilities Summary (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Amortizable Intangible Assets
Accumulated Amortization	$ (1,249,841)	$ (1,089,784)
Indefinite Lived Intangible Assets Including Goodwill
Total intangible assets, gross	3,955,395	3,940,026
Total intangible assets, net	2,705,554	2,850,242
Amortizable Intangible Liabilities
Less: accumulated amortization	89,516	74,484
Indefinite Lived Intangible Liabilities
Total intangible liabilities, gross	(281,961)	(285,226)
Total intangible liabilities, net	(192,445)	(210,742)
Below-market purchase option
Indefinite Lived Intangible Liabilities
Indefinite-lived intangible liabilities	(16,710)	(16,711)
Below-market rent
Amortizable Intangible Liabilities
Finite-lived intangible liabilities, gross	(265,251)	(268,515)
Less: accumulated amortization	89,516	74,484
Net amortizable intangible liabilities	(175,735)	(194,031)
Goodwill
Indefinite Lived Intangible Assets Including Goodwill
Indefinite-lived intangible assets	904,075	934,688
Contracts including internal software development costs
Amortizable Intangible Assets
Gross Carrying Amount	23,007	23,557
Accumulated Amortization	(17,542)	(15,482)
Net Carrying Amount	5,465	8,075
Internal-use software development costs
Amortizable Intangible Assets
Gross Carrying Amount	19,032	19,582
Accumulated Amortization	(14,955)	(13,491)
Net Carrying Amount	4,077	6,091
Trade name
Amortizable Intangible Assets
Gross Carrying Amount	3,975	3,975
Accumulated Amortization	(2,587)	(1,991)
Net Carrying Amount	1,388	1,984
Lease intangibles
Amortizable Intangible Assets
Gross Carrying Amount	3,028,313	2,981,781
Accumulated Amortization	(1,232,299)	(1,074,302)
Net Carrying Amount	1,796,014	1,907,479
In-place lease
Amortizable Intangible Assets
Gross Carrying Amount	2,127,810	2,072,642
Accumulated Amortization	(796,959)	(676,008)
Net Carrying Amount	1,330,851	1,396,634
Above-market rent
Amortizable Intangible Assets
Gross Carrying Amount	900,503	909,139
Accumulated Amortization	(435,340)	(398,294)
Net Carrying Amount	$ 465,163	$ 510,845