Summarized Condensed Consolidating Information - Condensed Consolidating Balance Sheets (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2015
Assets:
Real estate investments, net	$ 972,832	$ 893,918
Other real estate investments	5,192	13,872
Cash and cash equivalents	35,066	7,500	$ 9,644	$ 11,467
Accounts and other receivables	9,425	5,896
Prepaid expenses and other assets	5,282	1,369
Deferred financing costs, net	2,260	2,803
Investment in subsidiaries	0	0
Intercompany	0	0
Total assets	1,030,057	925,358
Liabilities and Equity:
Senior unsecured notes payable, net	294,043	255,294
Accounts payable and accrued liabilities	14,521	12,137
Dividends payable	14,048	11,075
Intercompany	0	0
Total liabilities	422,081	472,928
Equity:
Common stock, $0.01 par value; 500,000,000 shares authorized, 75,466,982 and 64,816,350 shares issued and outstanding as of June 30, 2017 and December 31, 2016, respectively	755	648
Additional paid-in capital	782,073	611,475
Cumulative distributions in excess of earnings	(174,852)	(159,693)
Total equity	607,976	452,430		262,288
Total liabilities and equity	1,030,057	925,358
Senior unsecured term loan, net
Liabilities and Equity:
Line of credit	99,469	99,422
Unsecured revolving credit facility
Liabilities and Equity:
Line of credit	0	95,000
Reportable Legal Entities [Member] | Parent Guarantor [Member]
Assets:
Real estate investments, net	0	0
Other real estate investments	0	0
Cash and cash equivalents	0	0	0	0
Accounts and other receivables	0	0
Prepaid expenses and other assets	0	0
Deferred financing costs, net	0	0
Investment in subsidiaries	622,024	463,505
Intercompany	0	0
Total assets	622,024	463,505
Liabilities and Equity:
Senior unsecured notes payable, net	0	0
Accounts payable and accrued liabilities	0	0
Dividends payable	14,048	11,075
Intercompany	0	0
Total liabilities	14,048	11,075
Equity:
Common stock, $0.01 par value; 500,000,000 shares authorized, 75,466,982 and 64,816,350 shares issued and outstanding as of June 30, 2017 and December 31, 2016, respectively	755	648
Additional paid-in capital	782,073	611,475
Cumulative distributions in excess of earnings	(174,852)	(159,693)
Total equity	607,976	452,430
Total liabilities and equity	622,024	463,505
Reportable Legal Entities [Member] | Parent Guarantor [Member] | Senior unsecured term loan, net
Liabilities and Equity:
Line of credit	0	0
Reportable Legal Entities [Member] | Parent Guarantor [Member] | Unsecured revolving credit facility
Liabilities and Equity:
Line of credit	0	0
Reportable Legal Entities [Member] | Issuers [Member]
Assets:
Real estate investments, net	617,036	527,639
Other real estate investments	0	0
Cash and cash equivalents	35,066	7,500	9,644	11,467
Accounts and other receivables	7,470	3,743
Prepaid expenses and other assets	5,280	1,366
Deferred financing costs, net	2,260	2,803
Investment in subsidiaries	424,123	401,328
Intercompany	0	0
Total assets	1,091,235	944,379
Liabilities and Equity:
Senior unsecured notes payable, net	294,043	255,294
Accounts payable and accrued liabilities	12,334	9,713
Dividends payable	0	0
Intercompany	63,365	21,445
Total liabilities	469,211	480,874
Equity:
Common stock, $0.01 par value; 500,000,000 shares authorized, 75,466,982 and 64,816,350 shares issued and outstanding as of June 30, 2017 and December 31, 2016, respectively	0	0
Additional paid-in capital	574,384	429,453
Cumulative distributions in excess of earnings	47,640	34,052
Total equity	622,024	463,505
Total liabilities and equity	1,091,235	944,379
Reportable Legal Entities [Member] | Issuers [Member] | Senior unsecured term loan, net
Liabilities and Equity:
Line of credit	99,469	99,422
Reportable Legal Entities [Member] | Issuers [Member] | Unsecured revolving credit facility
Liabilities and Equity:
Line of credit	0	95,000
Reportable Legal Entities [Member] | Combined Subsidiary Guarantors [Member]
Assets:
Real estate investments, net	355,796	366,279
Other real estate investments	5,192	13,872
Cash and cash equivalents	0	0	0	0
Accounts and other receivables	1,955	2,153
Prepaid expenses and other assets	2	3
Deferred financing costs, net	0	0
Investment in subsidiaries	0	0
Intercompany	63,365	21,445
Total assets	426,310	403,752
Liabilities and Equity:
Senior unsecured notes payable, net	0	0
Accounts payable and accrued liabilities	2,187	2,424
Dividends payable	0	0
Intercompany	0	0
Total liabilities	2,187	2,424
Equity:
Common stock, $0.01 par value; 500,000,000 shares authorized, 75,466,982 and 64,816,350 shares issued and outstanding as of June 30, 2017 and December 31, 2016, respectively	0	0
Additional paid-in capital	321,761	321,761
Cumulative distributions in excess of earnings	102,362	79,567
Total equity	424,123	401,328
Total liabilities and equity	426,310	403,752
Reportable Legal Entities [Member] | Combined Subsidiary Guarantors [Member] | Senior unsecured term loan, net
Liabilities and Equity:
Line of credit	0	0
Reportable Legal Entities [Member] | Combined Subsidiary Guarantors [Member] | Unsecured revolving credit facility
Liabilities and Equity:
Line of credit	0	0
Elimination [Member]
Assets:
Real estate investments, net	0	0
Other real estate investments	0	0
Cash and cash equivalents	0	0	$ 0	$ 0
Accounts and other receivables	0	0
Prepaid expenses and other assets	0	0
Deferred financing costs, net	0	0
Investment in subsidiaries	(1,046,147)	(864,833)
Intercompany	(63,365)	(21,445)
Total assets	(1,109,512)	(886,278)
Liabilities and Equity:
Senior unsecured notes payable, net	0	0
Accounts payable and accrued liabilities	0	0
Dividends payable	0	0
Intercompany	(63,365)	(21,445)
Total liabilities	(63,365)	(21,445)
Equity:
Common stock, $0.01 par value; 500,000,000 shares authorized, 75,466,982 and 64,816,350 shares issued and outstanding as of June 30, 2017 and December 31, 2016, respectively	0	0
Additional paid-in capital	(896,145)	(751,214)
Cumulative distributions in excess of earnings	(150,002)	(113,619)
Total equity	(1,046,147)	(864,833)
Total liabilities and equity	(1,109,512)	(886,278)
Elimination [Member] | Senior unsecured term loan, net
Liabilities and Equity:
Line of credit	0	0
Elimination [Member] | Unsecured revolving credit facility
Liabilities and Equity:
Line of credit	$ 0	$ 0