Equity - Shares Issued and Gross Proceeds (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Total redemptions (shares)	(3,297,240)
Total shares outstanding (in shares)	77,881,873	77,525,973
Class T
Class of Stock [Line Items]
Total redemptions (shares)	0
Total shares outstanding (in shares)	228,101	227,311
Class S
Class of Stock [Line Items]
Total redemptions (shares)	0
Total shares outstanding (in shares)	281	279
Class D
Class of Stock [Line Items]
Total redemptions (shares)	0
Total shares outstanding (in shares)	19,376	19,268
Class I
Class of Stock [Line Items]
Total redemptions (shares)	0
Total shares outstanding (in shares)	819,384	806,014
Class A
Class of Stock [Line Items]
Total redemptions (shares)	(1,528,918)
Total shares outstanding (in shares)	25,844,447	25,729,035
Class AA
Class of Stock [Line Items]
Total redemptions (shares)	(1,744,366)
Total shares outstanding (in shares)	49,990,960	49,768,687
Class AAA
Class of Stock [Line Items]
Total redemptions (shares)	(23,956)
Total shares outstanding (in shares)	979,324	975,379
IPO
Class of Stock [Line Items]
Gross proceeds received to date of shares issued	$ 733,987
Common stock, number of shares issued (in shares)	73,694,264
IPO | Class T
Class of Stock [Line Items]
Gross proceeds received to date of shares issued	$ 2,245
Common stock, number of shares issued (in shares)	224,647
IPO | Class S
Class of Stock [Line Items]
Gross proceeds received to date of shares issued	$ 3
Common stock, number of shares issued (in shares)	264
IPO | Class D
Class of Stock [Line Items]
Gross proceeds received to date of shares issued	$ 182
Common stock, number of shares issued (in shares)	18,921
IPO | Class I
Class of Stock [Line Items]
Gross proceeds received to date of shares issued	$ 7,538
Common stock, number of shares issued (in shares)	786,573
IPO | Class A
Class of Stock [Line Items]
Gross proceeds received to date of shares issued	$ 240,780
Common stock, number of shares issued (in shares)	24,199,764
IPO | Class AA
Class of Stock [Line Items]
Gross proceeds received to date of shares issued	$ 474,858
Common stock, number of shares issued (in shares)	47,562,870
IPO | Class AAA
Class of Stock [Line Items]
Gross proceeds received to date of shares issued	$ 8,381
Common stock, number of shares issued (in shares)	901,225
Distribution Reinvestment Plan
Class of Stock [Line Items]
Gross proceeds received to date of shares issued	$ 65,275
Common stock, number of shares issued (in shares)	6,869,864
Distribution Reinvestment Plan | Class T
Class of Stock [Line Items]
Gross proceeds received to date of shares issued	$ 33
Common stock, number of shares issued (in shares)	3,454
Distribution Reinvestment Plan | Class S
Class of Stock [Line Items]
Gross proceeds received to date of shares issued	$ 0
Common stock, number of shares issued (in shares)	17
Distribution Reinvestment Plan | Class D
Class of Stock [Line Items]
Gross proceeds received to date of shares issued	$ 4
Common stock, number of shares issued (in shares)	455
Distribution Reinvestment Plan | Class I
Class of Stock [Line Items]
Gross proceeds received to date of shares issued	$ 215
Common stock, number of shares issued (in shares)	22,311
Distribution Reinvestment Plan | Class A
Class of Stock [Line Items]
Gross proceeds received to date of shares issued	$ 27,645
Common stock, number of shares issued (in shares)	2,909,959
Distribution Reinvestment Plan | Class AA
Class of Stock [Line Items]
Gross proceeds received to date of shares issued	$ 36,795
Common stock, number of shares issued (in shares)	3,872,290
Distribution Reinvestment Plan | Class AAA
Class of Stock [Line Items]
Gross proceeds received to date of shares issued	$ 583
Common stock, number of shares issued (in shares)	61,378
Share Distribution
Class of Stock [Line Items]
Common stock, number of shares issued (in shares)	568,485
Share Distribution | Class T
Class of Stock [Line Items]
Common stock, number of shares issued (in shares)	0
Share Distribution | Class S
Class of Stock [Line Items]
Common stock, number of shares issued (in shares)	0
Share Distribution | Class D
Class of Stock [Line Items]
Common stock, number of shares issued (in shares)	0
Share Distribution | Class I
Class of Stock [Line Items]
Common stock, number of shares issued (in shares)	0
Share Distribution | Class A
Class of Stock [Line Items]
Common stock, number of shares issued (in shares)	263,642
Share Distribution | Class AA
Class of Stock [Line Items]
Common stock, number of shares issued (in shares)	300,166
Share Distribution | Class AAA
Class of Stock [Line Items]
Common stock, number of shares issued (in shares)	4,677
Restricted stock units issued
Class of Stock [Line Items]
Common stock, number of shares issued (in shares)	46,500
Restricted stock units issued | Class T
Class of Stock [Line Items]
Common stock, number of shares issued (in shares)	0
Restricted stock units issued | Class S
Class of Stock [Line Items]
Common stock, number of shares issued (in shares)	0
Restricted stock units issued | Class D
Class of Stock [Line Items]
Common stock, number of shares issued (in shares)	0
Restricted stock units issued | Class I
Class of Stock [Line Items]
Common stock, number of shares issued (in shares)	10,500
Restricted stock units issued | Class A
Class of Stock [Line Items]
Common stock, number of shares issued (in shares)	0
Restricted stock units issued | Class AA
Class of Stock [Line Items]
Common stock, number of shares issued (in shares)	0
Restricted stock units issued | Class AAA
Class of Stock [Line Items]
Common stock, number of shares issued (in shares)	36,000