Supplemental Cash Flow Information of the Company (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Supplemental Cash Flow Information [Abstract]
Cash paid for interest, net of capitalized interest of $13,815 and $10,669 as of March 31, 2016 and 2015, respectively	$ 13,797	$ 19,814
Noncash Investing Activities [Abstract]
Accrual for expenditures for operating properties and development properties	59,218	85,656
Tenant improvements funded directly by tenants	10,664	231
Assumption of accrued liabilities in connection with development acquisitions (Note 2)	4,741	1,478
Release of holdback funds to third party	0	8,279
Noncash Financing Activities [Abstract]
Issuance of common units of the Operating Partnership in connection with an acquisition (Note 2)	48,033	0
Accrual of dividends and distributions payable to common stockholders and common unitholders	33,677	31,892
Accrual of dividends and distributions payable to preferred stockholders and preferred unitholders	1,656	1,656
Exchange of common units of the Operating Partnership into shares of the Company’s common stock	39	316
Interest capitalized	$ 13,815	$ 10,669