Condensed Consolidated Statements of Cash Flows - Supplemental Information (Supplemental Information) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Supplemental Cash Flow Elements [Abstract]
Interest paid	$ 39,592	$ 31,601
Non-Cash Transactions:
Non-cash assets and liabilities assumed in TIER transaction	1,512,373	0
Ground lease right-of-use assets and associated liabilities	56,294	0
Common stock dividends declared and accrued	42,567	27,364
Change in accrued property, acquisition, development, and tenant expenditures	22,599	21,920
Non-cash consideration for property acquisition	10,071	0
Transfers from projects under development to operating properties	0	212,628
Cumulative effect of change in accounting principle	0	22,329
Transfer from investment in unconsolidated joint venture to projects under development	$ 0	$ 7,025