Summarized Condensed Consolidating Information - Condensed Consolidating Statements of Cash Flows (Details) - USD ($) $ in Thousands		12 Months Ended
	Apr. 15, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net cash (used in) provided by operating activities		$ 126,295	$ 99,357	$ 88,800
Cash flows from investing activities:
Acquisitions of real estate, net of deposits applied		(321,458)	(111,640)	(296,517)
Improvements to real estate		(3,352)	(7,230)	(748)
Purchases of equipment, furniture and fixtures		(2,937)	(1,782)	(403)
Investment in real estate mortgage and other loans receivable		(18,246)	(5,648)	(12,416)
Principal payments received on real estate mortgage and other loans receivable		24,283	3,227	25
Repayment of other real estate investment		2,204	0	7,500
Escrow deposits for acquisitions of real estate		0	(5,000)	0
Net proceeds from sales of real estate		3,499	13,004	0
Distribution from Subsidiary		0	0	0
Intercompany financing		0	0	0
Net cash used in investing activities		(316,007)	(115,069)	(302,559)
Cash flows from financing activities:
Proceeds from the issuance of common stock, net	$ 149,000	195,924	179,882	170,323
Proceeds from the issuance of senior unsecured notes payable		0	0	300,000
Proceeds from the issuance of senior unsecured term loan		200,000	0	0
Borrowings under unsecured revolving credit facility		243,000	65,000	238,000
Payments on senior unsecured notes payable		0	0	(267,639)
Payments on unsecured revolving credit facility		(278,000)	(135,000)	(168,000)
Payments on senior unsecured term loan		(100,000)	0	0
Payments of deferred financing costs		(4,534)	0	(6,063)
Net-settle adjustment on restricted stock		(2,524)	(1,288)	(866)
Dividends paid on common stock		(80,619)	(62,999)	(52,587)
Distribution to Parent		0	0	0
Intercompany financing		0	0	0
Net cash provided by financing activities		173,247	45,595	213,168
Net (decrease) increase in cash and cash equivalents		(16,465)	29,883	(591)
Cash and cash equivalents, beginning of period		36,792	6,909	7,500
Cash and cash equivalents, end of period		20,327	36,792	6,909
Reportable Legal Entities | Parent Guarantor
Cash flows from operating activities:
Net cash (used in) provided by operating activities		(114)	(10)	(222)
Cash flows from investing activities:
Acquisitions of real estate, net of deposits applied		0	0	0
Improvements to real estate		0	0	0
Purchases of equipment, furniture and fixtures		0	0	0
Investment in real estate mortgage and other loans receivable		0	0	0
Principal payments received on real estate mortgage and other loans receivable		0	0	0
Repayment of other real estate investment		0		0
Escrow deposits for acquisitions of real estate			0
Net proceeds from sales of real estate		0	0
Distribution from Subsidiary		80,619	62,999	52,587
Intercompany financing		(193,286)	(178,584)	(169,235)
Net cash used in investing activities		(112,667)	(115,585)	(116,648)
Cash flows from financing activities:
Proceeds from the issuance of common stock, net		195,924	179,882	170,323
Proceeds from the issuance of senior unsecured notes payable				0
Proceeds from the issuance of senior unsecured term loan		0
Borrowings under unsecured revolving credit facility		0	0	0
Payments on senior unsecured notes payable				0
Payments on unsecured revolving credit facility		0	0	0
Payments on senior unsecured term loan		0
Payments of deferred financing costs		0		0
Net-settle adjustment on restricted stock		(2,524)	(1,288)	(866)
Dividends paid on common stock		(80,619)	(62,999)	(52,587)
Distribution to Parent		0	0	0
Intercompany financing		0	0	0
Net cash provided by financing activities		112,781	115,595	116,870
Net (decrease) increase in cash and cash equivalents		0	0	0
Cash and cash equivalents, beginning of period		0	0	0
Cash and cash equivalents, end of period		0	0	0
Reportable Legal Entities | Issuers
Cash flows from operating activities:
Net cash (used in) provided by operating activities		49,681	40,092	25,745
Cash flows from investing activities:
Acquisitions of real estate, net of deposits applied		(109,294)	(111,640)	(296,517)
Improvements to real estate		(1,360)	(7,204)	(681)
Purchases of equipment, furniture and fixtures		(2,933)	(1,713)	(309)
Investment in real estate mortgage and other loans receivable		(18,246)	(5,648)	(12,416)
Principal payments received on real estate mortgage and other loans receivable		24,283	3,227	25
Repayment of other real estate investment		0		0
Escrow deposits for acquisitions of real estate			(5,000)
Net proceeds from sales of real estate		218	13,004
Distribution from Subsidiary		0	0	0
Intercompany financing		(131,947)	59,180	70,616
Net cash used in investing activities		(239,279)	(55,794)	(239,282)
Cash flows from financing activities:
Proceeds from the issuance of common stock, net		0	0	0
Proceeds from the issuance of senior unsecured notes payable				300,000
Proceeds from the issuance of senior unsecured term loan		200,000
Borrowings under unsecured revolving credit facility		243,000	65,000	238,000
Payments on senior unsecured notes payable				(267,639)
Payments on unsecured revolving credit facility		(278,000)	(135,000)	(168,000)
Payments on senior unsecured term loan		(100,000)
Payments of deferred financing costs		(4,534)		(6,063)
Net-settle adjustment on restricted stock		0	0	0
Dividends paid on common stock		0	0	0
Distribution to Parent		(80,619)	(62,999)	(52,587)
Intercompany financing		193,286	178,584	169,235
Net cash provided by financing activities		173,133	45,585	212,946
Net (decrease) increase in cash and cash equivalents		(16,465)	29,883	(591)
Cash and cash equivalents, beginning of period		36,792	6,909	7,500
Cash and cash equivalents, end of period		20,327	36,792	6,909
Reportable Legal Entities | Combined Subsidiary Guarantors
Cash flows from operating activities:
Net cash (used in) provided by operating activities		76,728	59,275	63,277
Cash flows from investing activities:
Acquisitions of real estate, net of deposits applied		(212,164)	0	0
Improvements to real estate		(1,992)	(26)	(67)
Purchases of equipment, furniture and fixtures		(4)	(69)	(94)
Investment in real estate mortgage and other loans receivable		0	0	0
Principal payments received on real estate mortgage and other loans receivable		0	0	0
Repayment of other real estate investment		2,204		7,500
Escrow deposits for acquisitions of real estate			0
Net proceeds from sales of real estate		3,281	0
Distribution from Subsidiary		0	0	0
Intercompany financing		0	0	0
Net cash used in investing activities		(208,675)	(95)	7,339
Cash flows from financing activities:
Proceeds from the issuance of common stock, net		0	0	0
Proceeds from the issuance of senior unsecured notes payable				0
Proceeds from the issuance of senior unsecured term loan		0
Borrowings under unsecured revolving credit facility		0	0	0
Payments on senior unsecured notes payable				0
Payments on unsecured revolving credit facility		0	0	0
Payments on senior unsecured term loan		0
Payments of deferred financing costs		0		0
Net-settle adjustment on restricted stock		0	0	0
Dividends paid on common stock		0	0	0
Distribution to Parent		0	0	0
Intercompany financing		131,947	(59,180)	(70,616)
Net cash provided by financing activities		131,947	(59,180)	(70,616)
Net (decrease) increase in cash and cash equivalents		0	0	0
Cash and cash equivalents, beginning of period		0	0	0
Cash and cash equivalents, end of period		0	0	0
Elimination
Cash flows from operating activities:
Net cash (used in) provided by operating activities		0	0	0
Cash flows from investing activities:
Acquisitions of real estate, net of deposits applied		0	0	0
Improvements to real estate		0	0	0
Purchases of equipment, furniture and fixtures		0	0	0
Investment in real estate mortgage and other loans receivable		0	0	0
Principal payments received on real estate mortgage and other loans receivable		0	0	0
Repayment of other real estate investment		0		0
Escrow deposits for acquisitions of real estate			0
Net proceeds from sales of real estate		0	0
Distribution from Subsidiary		(80,619)	(62,999)	(52,587)
Intercompany financing		325,233	119,404	98,619
Net cash used in investing activities		244,614	56,405	46,032
Cash flows from financing activities:
Proceeds from the issuance of common stock, net		0	0	0
Proceeds from the issuance of senior unsecured notes payable				0
Proceeds from the issuance of senior unsecured term loan		0
Borrowings under unsecured revolving credit facility		0	0	0
Payments on senior unsecured notes payable				0
Payments on unsecured revolving credit facility		0	0	0
Payments on senior unsecured term loan		0
Payments of deferred financing costs		0		0
Net-settle adjustment on restricted stock		0	0	0
Dividends paid on common stock		0	0	0
Distribution to Parent		80,619	62,999	52,587
Intercompany financing		(325,233)	(119,404)	(98,619)
Net cash provided by financing activities		(244,614)	(56,405)	(46,032)
Net (decrease) increase in cash and cash equivalents		0	0	0
Cash and cash equivalents, beginning of period		0	0	0
Cash and cash equivalents, end of period		$ 0	$ 0	$ 0