Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Cash flows from operating activities:
Net loss	$ (58,763)	$ (31,847)	$ (160,345)	$ (49,815)
Adjustments to reconcile net loss to net cash provided by operating activities:
Management fee	11,823	3,712	28,073	3,712
Performance participation allocation	12,447	5,711	29,796	10,952	$ 17,000
Performance participation allocation				10,952
Depreciation and amortization	103,758	40,359	262,708	65,145
Unrealized gain on changes in fair value of financial instruments			(8,761)	(993)
Other items			(880)	(20)
Change in assets and liabilities:
(Increase) / decrease in other assets			(53,117)	(10,824)
Increase / (decrease) in due to affiliates			234	3,859
Increase / (decrease) in accounts payable, accrued expenses, and other liabilities			81,340	22,244
Net cash provided by operating activities			179,048	44,260
Cash flows from investing activities:
Acquisitions of real estate			(5,693,880)	(2,245,885)
Capital improvements to real estate			(59,071)	(3,290)
Pre-acquisition costs				(9,201)
Purchase of real estate-related securities			(1,227,708)	(660,151)
Proceeds from settlement of real estate-related securities			124,396	16,596
Net cash used in investing activities			(6,856,263)	(2,901,931)
Cash flows from financing activities:
Proceeds from issuance of common stock			1,948,928	1,264,053
Offering costs paid			(31,316)	(15,388)
Subscriptions received in advance			180,425	98,435
Repurchase of common stock			(19,259)	(187)
Redemption of redeemable non-controlling interest			(8,400)	0
Borrowings from mortgage notes, term loans, and revolving credit facilities			5,632,422	1,055,913
Repayments from mortgage notes, term loans, and revolving credit facilities			(1,737,931)	0
Borrowings under repurchase agreements			954,892	491,026
Settlement of repurchase agreements			(96,025)	(12,571)
Borrowings from affiliate line of credit			1,135,900	617,650
Repayments on affiliate line of credit			(1,141,150)	(495,150)
Payment of deferred financing costs			(39,468)	(12,384)
Contributions from non-controlling interests			80,216	8,978
Distributions to non-controlling interests			(2,776)	0
Distributions			(38,075)	(6,203)
Net cash provided by financing activities			6,818,383	2,994,172
Net change in cash and cash equivalents and restricted cash			141,168	136,501
Cash and cash equivalents and restricted cash, beginning of period			157,729	200	200
Cash and cash equivalents and restricted cash, end of period	298,897	136,701	298,897	136,701	157,729
Reconciliation of cash and cash equivalents and restricted cash to the condensed consolidated balance sheets:
Cash and cash equivalents	75,529	30,820	75,529	30,820	31,166
Restricted cash	223,368	105,881	223,368	105,881	126,563
Cash and cash equivalents and restricted cash, end of period	$ 298,897	$ 136,701	298,897	136,701	$ 157,729
Non-cash investing and financing activities:
Assumption of mortgage notes in conjunction with acquisitions of real estate			197,290	107,369
Assumption of other liabilities in conjunction with acquisitions of real estate			51,094	17,093
Acquired non-controlling interests			12,802	0
Accrued capital expenditures and acquisition related costs			3,985	314
Accrued pre-acquisition costs			61	905
Accrued distributions			9,952	5,624
Accrued stockholder servicing fee due to affiliate			101,124	75,998
Accrued offering costs due to affiliate				7,552
Redeemable non-controlling interest issued as settlement of performance participation allocation			16,974	0
Allocation to redeemable non-controlling interest			1,826	0
Distribution reinvestment			66,899	13,494
Accrued common stock repurchases			$ 11,344	$ 152