Consolidated Statements of Cash Flows - Supplemental Information (Supplemental Cash Flows Information) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Supplemental Cash Flow Elements [Abstract]
Interest paid, net of amounts capitalized	$ 43,166	$ 30,572	$ 32,215
Income taxes paid	0	0	0
Non-Cash Transactions:
Transfer from projects under development to operating properties	325,490	58,928	0
Common stock dividends declared and accrued	27,326	25,202	0
Cumulative effect of change in accounting principle	22,329	0	0
Transfer from investment in unconsolidated joint ventures to projects under development	7,025	0	5,880
Change in accrued property acquisition, development, and tenant asset expenditures	(18,104)	5,965	7,918
Transfer from investment in unconsolidated joint venture to operating properties	0	68,498	0
Non-cash assets and liabilities assumed in Merger	0	0	1,856,255
Non-cash assets and liabilities distributed in Spin-Off	0	0	(948,306)
Mortgage note payable legally defeased	0	0	20,170
Transfer from land held to projects under development	$ 0	$ 0	$ 8,099