Summarized Condensed Consolidating Information - Condensed Consolidating Balance Sheets (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015
Assets:
Real estate investments, net	$ 940,355	$ 893,918
Other real estate investments	14,027	13,872
Cash and cash equivalents	1,283	7,500	$ 4,663	$ 11,467
Accounts and other receivables	7,932	5,896
Prepaid expenses and other assets	1,309	1,369
Deferred financing costs, net	2,532	2,803
Investment in subsidiaries	0	0
Intercompany	0	0
Total assets	967,438	925,358
Liabilities and Equity:
Senior unsecured notes payable, net	255,561	255,294
Accounts payable and accrued liabilities	14,063	12,137
Dividends payable	13,422	11,075
Intercompany	0	0
Total liabilities	409,491	472,928
Equity:
Common stock, $0.01 par value; 500,000,000 shares authorized, 72,000,297 and 64,816,350 shares issued and outstanding as of March 31, 2017 and December 31, 2016, respectively	720	648
Additional paid-in capital	720,061	611,475
Cumulative distributions in excess of earnings	(162,834)	(159,693)
Total equity	557,947	452,430		262,288
Total liabilities and equity	967,438	925,358
Senior unsecured term loan, net
Liabilities and Equity:
Line of credit	99,445	99,422
Unsecured revolving credit facility
Liabilities and Equity:
Line of credit	27,000	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	571,369	463,505
Intercompany	0	0
Total assets	571,369	463,505
Liabilities and Equity:
Senior unsecured notes payable, net	0	0
Accounts payable and accrued liabilities	0	0
Dividends payable	13,422	11,075
Intercompany	0	0
Total liabilities	13,422	11,075
Equity:
Common stock, $0.01 par value; 500,000,000 shares authorized, 72,000,297 and 64,816,350 shares issued and outstanding as of March 31, 2017 and December 31, 2016, respectively	720	648
Additional paid-in capital	720,061	611,475
Cumulative distributions in excess of earnings	(162,834)	(159,693)
Total equity	557,947	452,430
Total liabilities and equity	571,369	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	578,921	527,639
Other real estate investments	0	0
Cash and cash equivalents	1,283	7,500	4,663	11,467
Accounts and other receivables	5,749	3,743
Prepaid expenses and other assets	1,307	1,366
Deferred financing costs, net	2,532	2,803
Investment in subsidiaries	410,841	401,328
Intercompany	0	0
Total assets	1,000,633	944,379
Liabilities and Equity:
Senior unsecured notes payable, net	255,561	255,294
Accounts payable and accrued liabilities	11,683	9,713
Dividends payable	0	0
Intercompany	35,575	21,445
Total liabilities	429,264	480,874
Equity:
Common stock, $0.01 par value; 500,000,000 shares authorized, 72,000,297 and 64,816,350 shares issued and outstanding as of March 31, 2017 and December 31, 2016, respectively	0	0
Additional paid-in capital	526,486	429,453
Cumulative distributions in excess of earnings	44,883	34,052
Total equity	571,369	463,505
Total liabilities and equity	1,000,633	944,379
Reportable Legal Entities [Member] | Issuers [Member] | Senior unsecured term loan, net
Liabilities and Equity:
Line of credit	99,445	99,422
Reportable Legal Entities [Member] | Issuers [Member] | Unsecured revolving credit facility
Liabilities and Equity:
Line of credit	27,000	95,000
Reportable Legal Entities [Member] | Combined Subsidiary Guarantors [Member]
Assets:
Real estate investments, net	323,972	328,137
Other real estate investments	14,027	13,872
Cash and cash equivalents	0	0	0	0
Accounts and other receivables	1,924	2,020
Prepaid expenses and other assets	2	3
Deferred financing costs, net	0	0
Investment in subsidiaries	0	0
Intercompany	113,655	102,273
Total assets	453,580	446,305
Liabilities and Equity:
Senior unsecured notes payable, net	0	0
Accounts payable and accrued liabilities	2,121	2,291
Dividends payable	0	0
Intercompany	0	0
Total liabilities	2,121	2,291
Equity:
Common stock, $0.01 par value; 500,000,000 shares authorized, 72,000,297 and 64,816,350 shares issued and outstanding as of March 31, 2017 and December 31, 2016, respectively	0	0
Additional paid-in capital	374,660	374,660
Cumulative distributions in excess of earnings	76,799	69,354
Total equity	451,459	444,014
Total liabilities and equity	453,580	446,305
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
Reportable Legal Entities [Member] | Combined Non-Guarantor Subsidiaries [Member]
Assets:
Real estate investments, net	37,462	38,142
Other real estate investments	0	0
Cash and cash equivalents	0	0	0	0
Accounts and other receivables	259	133
Prepaid expenses and other assets	0	0
Deferred financing costs, net	0	0
Investment in subsidiaries	0	0
Intercompany	0	0
Total assets	37,721	38,275
Liabilities and Equity:
Senior unsecured notes payable, net	0	0
Accounts payable and accrued liabilities	259	133
Dividends payable	0	0
Intercompany	78,080	80,828
Total liabilities	78,339	80,961
Equity:
Common stock, $0.01 par value; 500,000,000 shares authorized, 72,000,297 and 64,816,350 shares issued and outstanding as of March 31, 2017 and December 31, 2016, respectively	0	0
Additional paid-in capital	(52,899)	(52,899)
Cumulative distributions in excess of earnings	12,281	10,213
Total equity	(40,618)	(42,686)
Total liabilities and equity	37,721	38,275
Reportable Legal Entities [Member] | Combined Non-Guarantor Subsidiaries [Member] | Senior unsecured term loan, net
Liabilities and Equity:
Line of credit	0	0
Reportable Legal Entities [Member] | Combined Non-Guarantor Subsidiaries [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	(982,210)	(864,833)
Intercompany	(113,655)	(102,273)
Total assets	(1,095,865)	(967,106)
Liabilities and Equity:
Senior unsecured notes payable, net	0	0
Accounts payable and accrued liabilities	0	0
Dividends payable	0	0
Intercompany	(113,655)	(102,273)
Total liabilities	(113,655)	(102,273)
Equity:
Common stock, $0.01 par value; 500,000,000 shares authorized, 72,000,297 and 64,816,350 shares issued and outstanding as of March 31, 2017 and December 31, 2016, respectively	0	0
Additional paid-in capital	(848,247)	(751,214)
Cumulative distributions in excess of earnings	(133,963)	(113,619)
Total equity	(982,210)	(864,833)
Total liabilities and equity	(1,095,865)	(967,106)
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