Summarized Condensed Consolidating Information - Condensed Consolidating Balance Sheets (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Assets:
Real estate investments, net	$ 1,259,336	$ 1,216,237
Other real estate investments, net	29,419	18,045
Cash and cash equivalents	214,354	36,792
Accounts and other receivables, net	8,360	11,387
Prepaid expenses and other assets	8,759	8,668
Deferred financing costs, net	3,758	633
Investment in subsidiaries	0	0
Intercompany	0	0
Total assets	1,523,986	1,291,762
Liabilities and Equity:
Senior unsecured notes payable, net	295,342	295,153
Senior unsecured term loan, net	198,555	99,612
Borrowings outstanding on revolving credit facility	185,000	95,000
Accounts payable and accrued liabilities	13,972	15,967
Dividends payable	20,086	17,783
Intercompany	0	0
Total liabilities	712,955	523,515
Equity:
Common stock, $0.01 par value; 500,000,000 shares authorized, 88,398,273 and 85,867,044 shares issued and outstanding as of March 31, 2019 and December 31, 2018, respectively	884	859
Additional paid-in capital	1,012,295	965,578
Cumulative distributions in excess of earnings	(202,148)	(198,190)
Total equity	811,031	768,247	$ 593,888	$ 594,617
Total liabilities and equity	1,523,986	1,291,762
Reportable Legal Entities | Parent Guarantor
Assets:
Real estate investments, net	0	0
Other real estate investments, net	0	0
Cash and cash equivalents	0	0
Accounts and other receivables, net	0	0
Prepaid expenses and other assets	0	0
Deferred financing costs, net	0	0
Investment in subsidiaries	831,117	786,030
Intercompany	0	0
Total assets	831,117	786,030
Liabilities and Equity:
Senior unsecured notes payable, net	0	0
Senior unsecured term loan, net	0	0
Borrowings outstanding on revolving credit facility	0	0
Accounts payable and accrued liabilities	0	0
Dividends payable	20,086	17,783
Intercompany	0	0
Total liabilities	20,086	17,783
Equity:
Common stock, $0.01 par value; 500,000,000 shares authorized, 88,398,273 and 85,867,044 shares issued and outstanding as of March 31, 2019 and December 31, 2018, respectively	884	859
Additional paid-in capital	1,012,295	965,578
Cumulative distributions in excess of earnings	(202,148)	(198,190)
Total equity	811,031	768,247
Total liabilities and equity	831,117	786,030
Reportable Legal Entities | Issuers
Assets:
Real estate investments, net	935,419	887,921
Other real estate investments, net	23,673	12,299
Cash and cash equivalents	214,354	36,792
Accounts and other receivables, net	8,350	9,359
Prepaid expenses and other assets	8,756	8,666
Deferred financing costs, net	3,758	633
Investment in subsidiaries	495,487	484,955
Intercompany	0	0
Total assets	1,689,797	1,440,625
Liabilities and Equity:
Senior unsecured notes payable, net	295,342	295,153
Senior unsecured term loan, net	198,555	99,612
Borrowings outstanding on revolving credit facility	185,000	95,000
Accounts payable and accrued liabilities	13,775	13,588
Dividends payable	0	0
Intercompany	166,008	151,242
Total liabilities	858,680	654,595
Equity:
Common stock, $0.01 par value; 500,000,000 shares authorized, 88,398,273 and 85,867,044 shares issued and outstanding as of March 31, 2019 and December 31, 2018, respectively	0	0
Additional paid-in capital	689,725	661,686
Cumulative distributions in excess of earnings	141,392	124,344
Total equity	831,117	786,030
Total liabilities and equity	1,689,797	1,440,625
Reportable Legal Entities | Combined Subsidiary Guarantors
Assets:
Real estate investments, net	323,917	328,316
Other real estate investments, net	5,746	5,746
Cash and cash equivalents	0	0
Accounts and other receivables, net	10	2,028
Prepaid expenses and other assets	3	2
Deferred financing costs, net	0	0
Investment in subsidiaries	0	0
Intercompany	166,008	151,242
Total assets	495,684	487,334
Liabilities and Equity:
Senior unsecured notes payable, net	0	0
Senior unsecured term loan, net	0	0
Borrowings outstanding on revolving credit facility	0	0
Accounts payable and accrued liabilities	197	2,379
Dividends payable	0	0
Intercompany	0	0
Total liabilities	197	2,379
Equity:
Common stock, $0.01 par value; 500,000,000 shares authorized, 88,398,273 and 85,867,044 shares issued and outstanding as of March 31, 2019 and December 31, 2018, respectively	0	0
Additional paid-in capital	321,761	321,761
Cumulative distributions in excess of earnings	173,726	163,194
Total equity	495,487	484,955
Total liabilities and equity	495,684	487,334
Elimination
Assets:
Real estate investments, net	0	0
Other real estate investments, net	0	0
Cash and cash equivalents	0	0
Accounts and other receivables, net	0	0
Prepaid expenses and other assets	0	0
Deferred financing costs, net	0	0
Investment in subsidiaries	(1,326,604)	(1,270,985)
Intercompany	(166,008)	(151,242)
Total assets	(1,492,612)	(1,422,227)
Liabilities and Equity:
Senior unsecured notes payable, net	0	0
Senior unsecured term loan, net	0	0
Borrowings outstanding on revolving credit facility	0	0
Accounts payable and accrued liabilities	0	0
Dividends payable	0	0
Intercompany	(166,008)	(151,242)
Total liabilities	(166,008)	(151,242)
Equity:
Common stock, $0.01 par value; 500,000,000 shares authorized, 88,398,273 and 85,867,044 shares issued and outstanding as of March 31, 2019 and December 31, 2018, respectively	0	0
Additional paid-in capital	(1,011,486)	(983,447)
Cumulative distributions in excess of earnings	(315,118)	(287,538)
Total equity	(1,326,604)	(1,270,985)
Total liabilities and equity	$ (1,492,612)	$ (1,422,227)