Summarized Condensed Consolidating and Combining Information - Condensed Consolidating Balance Sheets (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2013
Assets:
Real estate investments, net	$ 651,554	$ 436,215
Other real estate investments	8,229	7,532
Cash and cash equivalents	12,098	25,320	$ 88,845	$ 895
Accounts receivable	2,961	2,291
Prepaid expenses and other assets	337	809
Deferred financing costs, net	9,793	10,405
Investment in subsidiaries	0	0
Intercompany	0	0
Total assets	684,972	482,572
Liabilities and Equity:
Senior unsecured notes payable	260,000	260,000
Mortgage notes payable	95,696	98,205
Unsecured revolving credit facility	45,000	0
Accounts payable and accrued liabilities	12,010	6,959
Dividends payable	7,704	3,946
Intercompany	0	0
Total liabilities	420,410	369,110
Equity:
Common stock, $0.01 par value; 500,000,000 shares authorized, 47,650,952 and 31,251,157 shares issued and outstanding as of September 30, 2015 and December 31, 2014, respectively	477	313
Additional paid-in capital	409,790	246,041
Cumulative distributions in excess of earnings	(145,705)	(132,892)
Total equity	264,562	113,462		162,689
Total liabilities and equity	684,972	482,572
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 receivable	0	0
Prepaid expenses and other assets	0	0
Deferred financing costs, net	0	0
Investment in subsidiaries	272,545	117,408
Intercompany	0	0
Total assets	272,545	117,408
Liabilities and Equity:
Senior unsecured notes payable	0	0
Mortgage notes payable	0	0
Unsecured revolving credit facility	0
Accounts payable and accrued liabilities	279	0
Dividends payable	7,704	3,946
Intercompany	0	0
Total liabilities	7,983	3,946
Equity:
Common stock, $0.01 par value; 500,000,000 shares authorized, 47,650,952 and 31,251,157 shares issued and outstanding as of September 30, 2015 and December 31, 2014, respectively	477	313
Additional paid-in capital	409,790	246,041
Cumulative distributions in excess of earnings	(145,705)	(132,892)
Total equity	264,562	113,462
Total liabilities and equity	272,545	117,408
Reportable Legal Entities [Member] | Issuers [Member]
Assets:
Real estate investments, net	257,065	26,104
Other real estate investments	0	0
Cash and cash equivalents	12,098	25,320	88,845	0
Accounts receivable	217	0
Prepaid expenses and other assets	331	808
Deferred financing costs, net	9,384	9,808
Investment in subsidiaries	357,660	335,020
Intercompany	0	0
Total assets	636,755	397,060
Liabilities and Equity:
Senior unsecured notes payable	260,000	260,000
Mortgage notes payable	0	0
Unsecured revolving credit facility	45,000
Accounts payable and accrued liabilities	8,024	3,067
Dividends payable	0	0
Intercompany	51,186	16,585
Total liabilities	364,210	279,652
Equity:
Common stock, $0.01 par value; 500,000,000 shares authorized, 47,650,952 and 31,251,157 shares issued and outstanding as of September 30, 2015 and December 31, 2014, respectively	0	0
Additional paid-in capital	274,913	125,551
Cumulative distributions in excess of earnings	(2,368)	(8,143)
Total equity	272,545	117,408
Total liabilities and equity	636,755	397,060
Reportable Legal Entities [Member] | Combined Subsidiary Guarantors [Member]
Assets:
Real estate investments, net	352,816	366,199
Other real estate investments	8,229	7,532
Cash and cash equivalents	0	0	0	895
Accounts receivable	2,533	2,170
Prepaid expenses and other assets	6	1
Deferred financing costs, net	0	0
Investment in subsidiaries	0	0
Intercompany	47,722	15,262
Total assets	411,306	391,164
Liabilities and Equity:
Senior unsecured notes payable	0	0
Mortgage notes payable	0	557
Unsecured revolving credit facility	0
Accounts payable and accrued liabilities	3,057	3,308
Dividends payable	0	0
Intercompany	0	0
Total liabilities	3,057	3,865
Equity:
Common stock, $0.01 par value; 500,000,000 shares authorized, 47,650,952 and 31,251,157 shares issued and outstanding as of September 30, 2015 and December 31, 2014, respectively	0	0
Additional paid-in capital	374,660	374,660
Cumulative distributions in excess of earnings	33,589	12,639
Total equity	408,249	387,299
Total liabilities and equity	411,306	391,164
Reportable Legal Entities [Member] | Combined Non-Guarantor Subsidiaries [Member]
Assets:
Real estate investments, net	41,673	43,912
Other real estate investments	0	0
Cash and cash equivalents	0	0	0	0
Accounts receivable	211	121
Prepaid expenses and other assets	0	0
Deferred financing costs, net	409	597
Investment in subsidiaries	0	0
Intercompany	3,464	1,323
Total assets	45,757	45,953
Liabilities and Equity:
Senior unsecured notes payable	0	0
Mortgage notes payable	95,696	97,648
Unsecured revolving credit facility	0
Accounts payable and accrued liabilities	650	584
Dividends payable	0	0
Intercompany	0	0
Total liabilities	96,346	98,232
Equity:
Common stock, $0.01 par value; 500,000,000 shares authorized, 47,650,952 and 31,251,157 shares issued and outstanding as of September 30, 2015 and December 31, 2014, respectively	0	0
Additional paid-in capital	(52,899)	(52,899)
Cumulative distributions in excess of earnings	2,310	620
Total equity	(50,589)	(52,279)
Total liabilities and equity	45,757	45,953
Elimination [Member]
Assets:
Real estate investments, net	0	0
Other real estate investments	0	0
Cash and cash equivalents	0	0	$ 0	$ 0
Accounts receivable	0	0
Prepaid expenses and other assets	0	0
Deferred financing costs, net	0	0
Investment in subsidiaries	(630,205)	(452,428)
Intercompany	(51,186)	(16,585)
Total assets	(681,391)	(469,013)
Liabilities and Equity:
Senior unsecured notes payable	0	0
Mortgage notes payable	0	0
Unsecured revolving credit facility	0
Accounts payable and accrued liabilities	0	0
Dividends payable	0	0
Intercompany	(51,186)	(16,585)
Total liabilities	(51,186)	(16,585)
Equity:
Common stock, $0.01 par value; 500,000,000 shares authorized, 47,650,952 and 31,251,157 shares issued and outstanding as of September 30, 2015 and December 31, 2014, respectively	0	0
Additional paid-in capital	(596,674)	(447,312)
Cumulative distributions in excess of earnings	(33,531)	(5,116)
Total equity	(630,205)	(452,428)
Total liabilities and equity	$ (681,391)	$ (469,013)