Segment Information - Schedule of Reconciliation of Net Income Attributable to Parent (Details) - USD ($)	3 Months Ended				12 Months Ended
	Dec. 31, 2018	Jun. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Net income (loss) attributable to common shareholders					$ 39,924,000	$ (71,753,000)	$ 61,974,000
Depreciation and amortization					211,436,000	161,659,000	133,343,000
Corporate and other					33,728,000	39,350,000	48,753,000
Third-party real estate services					89,826,000	51,919,000	19,066,000
Share-based compensation related to Formation Transaction			$ 14,800,000	$ 14,400,000	36,030,000	29,251,000	0
Transaction and other costs	$ 15,600,000		12,600,000	104,100,000	27,706,000	127,739,000	6,476,000
Interest expense					74,447,000	58,141,000	51,781,000
Loss on extinguishment of debt		$ 4,500,000			5,153,000	701,000	0
Reduction of gain (gain) on bargain purchase		7,600,000	$ 3,400,000	$ (27,800,000)	7,606,000	(24,376,000)	0
Income tax benefit					(738,000)	(9,912,000)	1,083,000
Net (income) loss attributable to redeemable noncontrolling interests					6,710,000	(7,328,000)	0
Third-party real estate services, including reimbursements					98,699,000	63,236,000	33,882,000
Other income					6,358,000	5,167,000	5,381,000
Income (loss) from unconsolidated real estate ventures, net					39,409,000	(4,143,000)	(947,000)
Interest and other income (loss), net					15,168,000	1,788,000	2,992,000
Gains (Losses) on Sales of Investment Real Estate	$ 6,400,000	$ 33,400,000			52,183,000	0	0
Net loss attributable to noncontrolling interests					21,000	3,000	0
Consolidated NOI					$ 319,990,000	$ 289,340,000	$ 281,168,000