Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Cash Flows [Abstract]
Net income	$ 39,185	$ 69,771	$ 23,092
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	177,859	164,201	142,472
Other amortization	3,013	3,000	3,879
Share-based compensation	12,275	10,691	10,028
Amortization of straight-line rent receivable (lessor)	(3,000)	(4,281)	(6,072)
Amortization of straight-line rent on operating leases (lessee)	1,537	1,519	1,497
Gain on sales of real estate assets	(25,101)	(41,665)	(39,524)
Loss on extinguishment of debt			44,985
Impairment of real estate assets	5,617		5,385
Loss (income) from unconsolidated joint ventures	19	(4)	(7)
Distributions from unconsolidated joint ventures	381	182
Provision for bad debts, net		60	159
Changes in operating assets and liabilities:
Other assets, including right-of-use-assets	(8,573)	(3,998)	(2,156)
Accounts payable and accrued liabilities	2,752	4,731	(7,307)
Other liabilities	7,174	4,148	3,335
Net cash provided by operating activities	213,138	208,355	179,766
INVESTING ACTIVITIES
Acquisitions of real estate	(380,274)	(104,312)	(274,668)
Development of real estate	(25,985)	(26,728)	(14,911)
Additional long-lived assets	(64,670)	(70,807)	(80,613)
Investment in unconsolidated joint ventures			(8,701)
Proceeds from sales of real estate assets	52,401	96,812	119,426
Proceeds from notes receivable repayments		8	19
Net cash used in investing activities	(418,528)	(105,027)	(259,448)
FINANCING ACTIVITIES
Net borrowings on unsecured credit facility	31,000	73,000	82,000
Borrowings on term loan	50,000		0
Borrowings of notes and bonds payable			297,459
Repayments of notes and bonds payable	(13,857)	(19,850)	(5,829)
Redemption of notes and bonds payable			(442,774)
Dividends paid	(155,358)	(150,266)	(142,327)
Net proceeds from issuance of common stock	295,946	611	248,554
Common stock redemptions	(5,097)	(4,532)	(1,686)
Debt issuance and assumption costs	(4,589)	(125)	(4,007)
Payments made on finance leases	(379)		0
Net cash provided by (used in) financing activities	197,666	(101,162)	31,390
(Decrease) increase in cash and cash equivalents	(7,724)	2,166	(48,292)
Cash and cash equivalents at beginning of period	8,381	6,215	54,507
Cash and cash equivalents at end of period	657	8,381	6,215
Supplemental Cash Flow Information
Interest paid	53,978	45,752	64,395
Mortgage notes payable assumed upon acquisition (adjusted to fair value)		7,995	43,674
Invoices accrued for construction, tenant improvements and other capitalized costs	17,294	12,682	8,303
Capitalized interest	$ 1,411	$ 951	$ 871