Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
OPERATING ACTIVITIES
Net income	$ 57,070	$ 21,300
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	71,504	63,280
Stock-based compensation	5,067	3,798
Amortization of straight-line rent receivable	(3,534)	(4,223)
Amortization of straight-line rent liability	316	368
Gain on sales of real estate assets	(39,532)	(8)
Impairment of real estate assets	328
Provision for bad debts, net	171	39
Changes in operating assets and liabilities:
Other assets	536	3,139
Accounts payable and accrued liabilities	(10,236)	(7,927)
Other liabilities	2,281	(20,287)
Net cash provided by operating activities	83,971	59,479
INVESTING ACTIVITIES
Acquisitions of real estate	(53,536)	(63,172)
Development of real estate	(10,098)	(18,982)
Additional long-lived assets	(36,329)	(29,286)
Proceeds from sales of real estate	117,010
Proceeds from mortgages and notes receivable repayments	10	9
Net cash provided by (used in) investing activities	17,057	(111,431)
FINANCING ACTIVITIES
Net repayments on unsecured credit facility	(72,000)	(16,000)
Borrowings of notes and bonds payable		11,500
Repayments on notes and bonds payable	(2,249)	(19,963)
Dividends paid	(69,898)	(62,239)
Net proceeds from issuance of common stock	1,005	145,125
Common stock redemptions	(1,125)	(1,282)
Debt issuance and assumption costs	(84)	(265)
Net cash (used in) provided by financing activities	(144,351)	56,876
(Decrease) increase in cash, cash equivalents and restricted cash	(43,323)	4,924
Cash, cash equivalents and restricted cash at beginning of period	54,507	4,102
Cash, cash equivalents and restricted cash at beginning of period	11,184	9,026
Supplemental Cash Flow Information:
Interest paid	27,570	28,692
Invoices accrued for construction, tenant improvements and other capitalized costs	6,355	12,745
Mortgage notes payable assumed upon acquisition (adjusted to fair value)	12,460	13,951
Capitalized interest	$ 484	$ 452