Consolidated Statements Of Cash Flows - USD ($)	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash flows from operating activities:
Net income	$ 117,251,000	$ 121,566,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	53,282,000	50,006,000
Amortization	3,229,000	4,154,000
Amortization of commitment fees	(625,000)	(393,000)
Amortization of lease incentives	240,000	69,000
Straight-line rental income	(17,516,000)	(18,956,000)
Non-cash interest income on construction loan	(1,257,000)	(708,000)
Gain on sale of real estate	0	(50,000)
Loss on modification and extinguishment of debt	738,000	591,000
Gain on sale of marketable securities	0	(10,038,000)
Loan and realty losses	1,849,000	0
Payment of lease incentives	(3,000,000)	(2,250,000)
Share-based compensation	2,131,000	2,270,000
Change in operating assets and liabilities:
Other assets	(3,664,000)	(2,575,000)
Accounts payable and accrued expenses	3,340,000	2,274,000
Net cash provided by operating activities	155,998,000	145,960,000
Cash flows from investing activities:
Investment in mortgage and other notes receivable	(16,144,000)	(44,729,000)
Collection of mortgage and other notes receivable	3,640,000	30,025,000
Investment in real estate	(129,558,000)	(133,251,000)
Investment in real estate development	0	(9,901,000)
Investment in renovations of existing real estate	(7,412,000)	(5,614,000)
Proceeds from disposition of real estate properties	0	450,000
Proceeds from sales of marketable securities	0	18,182,000
Net cash used in investing activities	(149,474,000)	(144,838,000)
Cash flows from financing activities:
Proceeds from revolving credit facilities	211,000,000	193,000,000
Payments on revolving credit facilities	(409,000,000)	(184,000,000)
Borrowings on term loan	300,000,000	250,000,000
Payments on term loans	(854,000)	(250,593,000)
Debt issuance costs	2,113,000	4,149,000
Value of shares withheld from options exercised for employee tax withholding	(730,000)	(586,000)
Proceeds from issuance of common shares, net	47,893,000	122,198,000
Consideration provided in convertible bond repurchase	(29,985,000)	(14,312,000)
Dividends paid to stockholders	(123,160,000)	(113,586,000)
Net cash provided by (used in) financing activities	(6,949,000)	(2,028,000)
(Decrease) increase in cash and cash equivalents	(425,000)	(906,000)
Cash and cash equivalents, beginning of year	3,063,000	4,832,000
Cash and cash equivalents, end of year	2,638,000
Supplemental disclosure of cash flow information:
Interest Paid	32,680,000	31,414,000
Supplemental schedule of non-cash investing and financing activities:
Accounts payable related to investments in real estate	568,000	1,500,000
Tenant investment in leased asset	$ 3,775,000	$ 1,250,000