Real Estate and Accumulated Depreciation (Notes to Schedule III) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Real Estate
Balance at beginning of period	$ 4,121,286	$ 3,893,799	$ 3,814,986
Additions during the period:
TIER merger	2,222,989	0	0
Acquisitions	542,502	48,920	62,723
Improvements and other capitalized costs	271,720	178,567	303,940
Total Additions	3,037,211	227,487	366,663
Deductions during the period:
Cost of real estate sold	(428)	0	(287,850)
Total Deductions	428	0	287,850
Balance at end of period	7,158,069	4,121,286	3,893,799
Accumulated Depreciation
Balance at beginning of period	421,495	275,977	215,856
Additions during the period:
Depreciation expense	200,122	145,518	101,720
Total Additions	200,122	145,518	101,720
Deductions during the period:
Cost of real estate sold	0	0	(41,599)
Total Deductions	0	0	(41,599)
Balance at end of period	621,617	$ 421,495	$ 275,977
Aggregate cost for federal income tax, net of depreciation	$ 4,900,000
Buildings and Improvements | Minimum
Deductions during the period:
Useful life	30 years
Buildings and Improvements | Maximum
Deductions during the period:
Useful life	42 years