Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash flows from operating activities:
Net income	$ 71,982,000	$ 80,867,000	$ 46,359,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization (including below-market ground leases)	55,394,000	52,819,000	51,866,000
Amortization of deferred financing costs	2,052,000	1,950,000	2,003,000
Loss on extinguishment of debt	10,827,000	0	0
Amortization of stock-based compensation	10,832,000	3,790,000	4,104,000
Straight-line rental income	(32,000)	(77,000)	(1,385,000)
Adjustment for collectibility of rental income	0	0	11,774,000
Noncash interest income	(155,000)	0	(797,000)
Loss (gain) on sale of real estate	77,000	37,000	(1,777,000)
Interest income distribution from other real estate investment	0	1,346,000	463,000
Impairment of real estate investments	0	0	16,692,000
Provision for loan losses	0	0	1,076,000
Change in operating assets and liabilities:
Accounts and other receivables	(562,000)	825,000	(6,283,000)
Prepaid expenses and other assets, net	399,000	387,000	(495,000)
Accounts payable, accrued liabilities and deferred rent liabilities	6,057,000	3,791,000	2,695,000
Net cash provided by operating activities	156,871,000	145,735,000	126,295,000
Cash flows from investing activities:
Acquisitions of real estate, net of deposits applied	(192,718,000)	(89,650,000)	(321,458,000)
Purchases of equipment, furniture and fixtures and improvements to real estate	(6,013,000)	(8,297,000)	(6,289,000)
Investment in real estate mortgage and other loans receivable	(1,253,000)	(30,498,000)	(18,246,000)
Principal payments received on real estate mortgage and other loans receivable	393,000	80,928,000	24,283,000
Repayment of other real estate investment	0	2,327,000	2,204,000
Escrow deposits for potential acquisitions of real estate	0	(3,000,000)	0
Net proceeds from sales of real estate	6,958,000	6,608,000	3,499,000
Net cash used in investing activities	(192,633,000)	(41,582,000)	(316,007,000)
Cash flows from financing activities:
Proceeds from (costs paid for) the issuance of common stock, net	22,946,000		195,924,000
Proceeds from (costs paid for) the issuance of common stock, net		(404,000)
Proceeds from the issuance of senior unsecured notes payable	400,000,000	0	0
Proceeds from the issuance of senior unsecured term loan	0	0	200,000,000
Borrowings under unsecured revolving credit facility	220,000,000	65,000,000	243,000,000
Payments on senior unsecured notes payable	(300,000,000)	0	0
Payments on senior unsecured term loan	0	0	(100,000,000)
Payments on unsecured revolving credit facility	(190,000,000)	(75,000,000)	(278,000,000)
Payments on debt extinguishment and deferred financing costs	(14,095,000)	0	(4,534,000)
Net-settle adjustment on restricted stock	(1,331,000)	(1,996,000)	(2,524,000)
Dividends paid on common stock	(100,782,000)	(93,161,000)	(80,619,000)
Net cash provided by (used in) financing activities	36,738,000	(105,561,000)	173,247,000
Net increase (decrease) in cash and cash equivalents	976,000	(1,408,000)	(16,465,000)
Cash and cash equivalents as of the beginning of period	18,919,000	20,327,000	36,792,000
Cash and cash equivalents as of the end of period	19,895,000	18,919,000	20,327,000
Supplemental disclosures of cash flow information:
Interest paid	22,838,000	21,691,000	26,005,000
Supplemental schedule of noncash investing and financing activities:
Increase in dividends payable	2,033,000	2,568,000	3,900,000
Right-of-use asset obtained in exchange for new operating lease obligation	0	599,000	1,010,000
Transfer of pre-acquisition costs to acquired assets	358,000	168,000	242,000
Sale of real estate settled with notes receivable	$ 0	$ 32,400,000	$ 27,500,000