Schedule III - Real Estate and Accumulated Depreciation - Activity in Real Estate Facilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Real estate, gross:
Balance at end of year	$ 9,170,716
Accumulated depreciation:
Balance at end of year	1,473,852
Net real estate assets:
Net non-lease real estate assets	7,696,864	$ 7,491,831	$ 7,132,431
Right of use asset - finance lease	8,050
Aggregate cost of real estate for U.S. federal income tax purposes	7,721,422
Operating facilities
Real estate, gross:
Balance at beginning of year	8,709,315	8,158,741	7,649,448
Acquisitions	303,588	459,223	628,391
Improvements	68,459	64,336	71,090
Transfers from construction in progress (to operating facilities)	59,614	49,449	19,079
Dispositions and other	(11,418)	(22,434)	(209,267)
Balance at end of year	9,129,558	8,709,315	8,158,741
Accumulated depreciation:
Balance at beginning of year	1,262,438	1,060,060	900,861
Depreciation expense	212,202	203,030	185,903
Dispositions and other	(789)	(652)	(26,704)
Balance at end of year	1,473,851	1,262,438	1,060,060
Real estate under development/redevelopment
Real estate, gross:
Balance at beginning of year	44,954	33,750	21,860
Current development	55,817	60,677	33,484
Transfers from construction in progress (to operating facilities)	(59,614)	(49,449)	(19,079)
Dispositions and other	0	(24)	(2,515)
Balance at end of year	$ 41,157	$ 44,954	$ 33,750