Consolidated Statements Of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net income	$ 185,311,000	$ 160,449,000	$ 154,333,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	83,150,000	76,816,000	71,349,000
Amortization	5,392,000	5,117,000	4,437,000
Amortization of commitment fees and note receivable discounts	(867,000)	(493,000)	(662,000)
Amortization of Lease Incentives	987,000	845,000	387,000
Straight-line rental income	(20,411,000)	(22,084,000)	(22,787,000)
Non-cash interest income on construction loan	(3,839,000)	(2,204,000)	(1,680,000)
Gain on sale of real estate	(21,316,000)	0	0
Loss on extinguishment of debt	3,924,000	823,000	738,000
Income (Loss) from Equity Method Investments	3,126,000	0	0
Loan and realty losses (recoveries), net	(991,000)	(2,440,000)	(5,115,000)
Payment of lease incentives	(623,000)	(3,100,000)	(5,280,000)
Share-based compensation	3,061,000	3,646,000	2,490,000
Change in operating assets and liabilities:
Equity-method investment and other assets	160,000	1,604,000	(5,298,000)
Accounts payable and accrued expenses	(6,681,000)	300,000	4,587,000
Deferred income	(217,000)	16,796,000	140,000
Net cash provided by operating activities	232,148,000	240,955,000	207,869,000
Cash flows from investing activities:
Investment in mortgage and other notes receivable	(58,356,000)	(108,232,000)	(106,991,000)
Collection of mortgage and other notes receivable	46,612,000	2,897,000	4,346,000
Investment in real estate	(102,712,000)	(219,187,000)	(131,758,000)
Investment in real estate development	(158,000)	0	0
Investment in renovations of existing real estate	(13,854,000)	(17,999,000)	(15,887,000)
Payments to Acquire Equity Method Investments	875,000	0	0
Proceeds from disposition of real estate properties	39,631,000	0	0
Net cash used in investing activities	89,712,000	342,521,000	250,290,000
Cash flows from financing activities:
Payments on revolving credit facility	205,000,000	397,000,000	306,000,000
Payments on revolving credit facility	(207,000,000)	(181,000,000)	(443,000,000)
Borrowings on term loan	100,000,000	0	300,000,000
Payments of term loans	(43,729,000)	(1,187,000)	(1,144,000)
Payment for Debt Extinguishment or Debt Prepayment Cost	(1,619,000)	0	0
Debt issuance costs	(1,039,000)	(126,000)	(2,171,000)
Distributions to noncontrolling interest	(748,000)	(15,000)	0
Proceeds for noncontrolling interest	13,000	643,000	0
Taxes remitted in relation to employee stock options exercised	(2,705,000)	(1,559,000)	(1,835,000)
Proceeds from equity offering, net	34,649,000	95,774,000	81,784,000
Convertible bond redemption	0	(22,468,000)	(29,985,000)
Dividends paid to stockholders	(194,584,000)	(179,739,000)	(165,391,000)
Net cash provided by (used in) financing activities	(111,762,000)	107,323,000	44,258,000
Increase (decrease) in cash and cash equivalents	30,674,000	5,757,000	1,837,000
Cash and cash equivalents and restricted cash, beginning of period	15,669,000	9,912,000	8,075,000
Cash and cash equivalents and restricted cash, end of period	46,343,000	15,669,000	9,912,000
Supplemental disclosure of cash flow information:
Interest paid, net of amounts capitalized	43,406,000	54,027,000	45,882,000
Supplemental schedule of non-cash investing and financing activities:
Change in straight-line rent receivable related to investments in real estate	0	38,000,000	0
Reclass of note balance into real estate investment	63,220,000	14,000,000	0
Noncontrolling Interest, Noncash Increase from Subsidiary Equity Issuance	10,778,000	0	0
Increase in mortgage note receivable from sale of real estate	4,000,000	0	0
Change in other assets related to investments in real estate	348,000	291,000	0
Change in accounts payable related to investments in real estate construction	0	(1,082,000)	0
Change in accounts payable related to investments in real estate acquisition	0	2,911,000	1,689,000
Change in Accounts Payable, Renovations of existing real estate	784,000	0	0
Change in accounts payable related to distributions to noncontrolling interests	138,000	0	0
Tenant investment in leased asset	0	0	3,775,000
Tenant forfeiture of lease escrow deposit	0	0	10,637,000
Settlement of contingent asset acquisition liability	$ 0	$ 0	$ 750,000