Equity - Shares Issued and Gross Proceeds (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Class of Stock [Line Items]
Total redemptions (shares)	(1,008,029)
Total shares outstanding (in shares)	77,567,145	77,175,283
Class T
Class of Stock [Line Items]
Total redemptions (shares)	0
Total shares outstanding (in shares)	26,316	4,148
Class S
Class of Stock [Line Items]
Total redemptions (shares)	0
Total shares outstanding (in shares)	271	268
Class D
Class of Stock [Line Items]
Total redemptions (shares)	0
Total shares outstanding (in shares)	796	268
Class I
Class of Stock [Line Items]
Total redemptions (shares)	0
Total shares outstanding (in shares)	283,845	267,476
Class A
Class of Stock [Line Items]
Total redemptions (shares)	(695,741)
Total shares outstanding (in shares)	26,051,325	25,995,943
Class AA
Class of Stock [Line Items]
Total redemptions (shares)	(312,288)
Total shares outstanding (in shares)	50,233,320	49,942,471
Class AAA
Class of Stock [Line Items]
Total redemptions (shares)	0
Total shares outstanding (in shares)	971,272	964,709
IPO
Class of Stock [Line Items]
Gross proceeds received to date of shares issued	$ 726,901
Common stock, number of shares issued (in shares)	72,966,905
IPO | Class T
Class of Stock [Line Items]
Gross proceeds received to date of shares issued	$ 260
Common stock, number of shares issued (in shares)	26,234
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	$ 8
Common stock, number of shares issued (in shares)	786
IPO | Class I
Class of Stock [Line Items]
Gross proceeds received to date of shares issued	$ 2,613
Common stock, number of shares issued (in shares)	275,765
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)	24,199,760
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	$ 8,379
Common stock, number of shares issued (in shares)	901,226
Distribution Reinvestment Plan
Class of Stock [Line Items]
Gross proceeds received to date of shares issued	$ 47,437
Common stock, number of shares issued (in shares)	5,014,286
Distribution Reinvestment Plan | Class T
Class of Stock [Line Items]
Gross proceeds received to date of shares issued	$ 1
Common stock, number of shares issued (in shares)	82
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)	7
Distribution Reinvestment Plan | Class D
Class of Stock [Line Items]
Gross proceeds received to date of shares issued	$ 0
Common stock, number of shares issued (in shares)	10
Distribution Reinvestment Plan | Class I
Class of Stock [Line Items]
Gross proceeds received to date of shares issued	$ 77
Common stock, number of shares issued (in shares)	8,080
Distribution Reinvestment Plan | Class A
Class of Stock [Line Items]
Gross proceeds received to date of shares issued	$ 21,626
Common stock, number of shares issued (in shares)	2,283,665
Distribution Reinvestment Plan | Class AA
Class of Stock [Line Items]
Gross proceeds received to date of shares issued	$ 25,358
Common stock, number of shares issued (in shares)	2,682,572
Distribution Reinvestment Plan | Class AAA
Class of Stock [Line Items]
Gross proceeds received to date of shares issued	$ 375
Common stock, number of shares issued (in shares)	39,870
Share Distribution
Class of Stock [Line Items]
Common stock, number of shares issued (in shares)	568,483
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)	263,641
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)	4,676
Restricted stock units issued
Class of Stock [Line Items]
Common stock, number of shares issued (in shares)	25,500
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)	0
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)	25,500