Summarized Condensed Consolidating Information - Condensed Consolidating Balance Sheets (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
Assets:
Real estate investments, net	$ 1,089,089	$ 893,918
Other real estate investments	5,368	13,872
Cash and cash equivalents	14,808	7,500	$ 11,878	$ 11,467
Accounts and other receivables	12,961	5,896
Prepaid expenses and other assets	1,803	1,369
Deferred financing costs, net	1,989	2,803
Investment in subsidiaries	0	0
Intercompany	0	0
Total assets	1,126,018	925,358
Liabilities and Equity:
Senior unsecured notes payable, net	294,221	255,294
Senior unsecured term loan, net	99,493	99,422
Unsecured revolving credit facility	95,000	95,000
Accounts payable and accrued liabilities	17,382	12,137
Dividends payable	14,046	11,075
Intercompany	0	0
Total liabilities	520,142	472,928
Equity:
Common stock, $0.01 par value; 500,000,000 shares authorized, 75,472,682 and 64,816,350 shares issued and outstanding as of September 30, 2017 and December 31, 2016, respectively	755	648
Additional paid-in capital	782,707	611,475
Cumulative distributions in excess of earnings	(177,586)	(159,693)
Total equity	605,876	452,430		262,288
Total liabilities and equity	1,126,018	925,358
Reportable Legal Entities | Parent Guarantor
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	619,922	463,505
Intercompany	0	0
Total assets	619,922	463,505
Liabilities and Equity:
Senior unsecured notes payable, net	0	0
Senior unsecured term loan, net	0	0
Unsecured revolving credit facility	0	0
Accounts payable and accrued liabilities	0	0
Dividends payable	14,046	11,075
Intercompany	0	0
Total liabilities	14,046	11,075
Equity:
Common stock, $0.01 par value; 500,000,000 shares authorized, 75,472,682 and 64,816,350 shares issued and outstanding as of September 30, 2017 and December 31, 2016, respectively	755	648
Additional paid-in capital	782,707	611,475
Cumulative distributions in excess of earnings	(177,586)	(159,693)
Total equity	605,876	452,430
Total liabilities and equity	619,922	463,505
Reportable Legal Entities | Issuers
Assets:
Real estate investments, net	738,013	527,639
Other real estate investments	0	0
Cash and cash equivalents	14,808	7,500	11,878	11,467
Accounts and other receivables	10,114	3,743
Prepaid expenses and other assets	1,801	1,366
Deferred financing costs, net	1,989	2,803
Investment in subsidiaries	434,113	401,328
Intercompany	0	0
Total assets	1,200,838	944,379
Liabilities and Equity:
Senior unsecured notes payable, net	294,221	255,294
Senior unsecured term loan, net	99,493	99,422
Unsecured revolving credit facility	95,000	95,000
Accounts payable and accrued liabilities	14,230	9,713
Dividends payable	0	0
Intercompany	77,972	21,445
Total liabilities	580,916	480,874
Equity:
Common stock, $0.01 par value; 500,000,000 shares authorized, 75,472,682 and 64,816,350 shares issued and outstanding as of September 30, 2017 and December 31, 2016, respectively	0	0
Additional paid-in capital	560,299	429,453
Cumulative distributions in excess of earnings	59,623	34,052
Total equity	619,922	463,505
Total liabilities and equity	1,200,838	944,379
Reportable Legal Entities | Combined Subsidiary Guarantors
Assets:
Real estate investments, net	351,076	366,279
Other real estate investments	5,368	13,872
Cash and cash equivalents	0	0	0	0
Accounts and other receivables	2,847	2,153
Prepaid expenses and other assets	2	3
Deferred financing costs, net	0	0
Investment in subsidiaries	0	0
Intercompany	77,972	21,445
Total assets	437,265	403,752
Liabilities and Equity:
Senior unsecured notes payable, net	0	0
Senior unsecured term loan, net	0	0
Unsecured revolving credit facility	0	0
Accounts payable and accrued liabilities	3,152	2,424
Dividends payable	0	0
Intercompany	0	0
Total liabilities	3,152	2,424
Equity:
Common stock, $0.01 par value; 500,000,000 shares authorized, 75,472,682 and 64,816,350 shares issued and outstanding as of September 30, 2017 and December 31, 2016, respectively	0	0
Additional paid-in capital	321,761	321,761
Cumulative distributions in excess of earnings	112,352	79,567
Total equity	434,113	401,328
Total liabilities and equity	437,265	403,752
Elimination
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	(1,054,035)	(864,833)
Intercompany	(77,972)	(21,445)
Total assets	(1,132,007)	(886,278)
Liabilities and Equity:
Senior unsecured notes payable, net	0	0
Senior unsecured term loan, net	0	0
Unsecured revolving credit facility	0	0
Accounts payable and accrued liabilities	0	0
Dividends payable	0	0
Intercompany	(77,972)	(21,445)
Total liabilities	(77,972)	(21,445)
Equity:
Common stock, $0.01 par value; 500,000,000 shares authorized, 75,472,682 and 64,816,350 shares issued and outstanding as of September 30, 2017 and December 31, 2016, respectively	0	0
Additional paid-in capital	(882,060)	(751,214)
Cumulative distributions in excess of earnings	(171,975)	(113,619)
Total equity	(1,054,035)	(864,833)
Total liabilities and equity	$ (1,132,007)	$ (886,278)