Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Cash flows from operating activities:
Net income (loss)	$ 25,571	$ 44,123
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation of buildings and tenant improvements	71,393	70,548
Amortization of deferred leasing and other costs	26,871	29,232
Amortization of deferred financing costs	2,499	3,507
Straight-line rental income and expense, net	(5,974)	(4,839)
Gain on acquisitions	0	(962)
Gains on land and depreciated property sales	(30,106)	(9,122)
Third-party construction contracts, net	411	11,138
Other accrued revenues and expenses, net	(33,911)	(26,261)
Operating distributions received in excess of (less than) equity in earnings from unconsolidated companies	2,383	(43,930)
Net cash provided by operating activities	59,137	73,434
Cash flows from investing activities:
Development of real estate investments	(105,413)	(103,684)
Acquisition of real estate investments and related intangible assets	(17,224)	(35,495)
Acquisition of undeveloped land	(2,270)	(5,149)
Second generation tenant improvements, leasing costs and building improvements	(19,631)	(17,119)
Other deferred leasing costs	(8,706)	(11,079)
Other assets	5,539	(5,124)
Proceeds from land and depreciated property sales, net	70,673	61,931
Capital distributions from unconsolidated companies	2,546	89,237
Capital contributions and advances to unconsolidated companies	(420)	(4,846)
Net cash provided by (used for) investing activities	(74,906)	(31,328)
Cash flows from financing activities:
Proceeds from issuance of common shares, net	23,783	574,685
Payments for redemption/repurchase of preferred shares/units	(17,656)	(177,955)
Proceeds from unsecured debt	0	250,000
Payments on unsecured debt	(511)	(480)
Proceeds from secured debt financings	0	1,933
Payments on secured indebtedness including principal amortization	(21,471)	(17,486)
Borrowings (payments) on line of credit, net	92,000	(285,000)
Distributions to common shareholders/unitholders	(55,596)	(54,678)
Distributions to preferred shareholders/unitholders	(7,140)	(9,550)
Distributions to Noncontrolling Interest, Net	(770)	(961)
Change in book overdrafts	3,629	(45,272)
Deferred financing costs	(300)	(4,064)
Net cash provided by (used for) financing activities	15,968	231,172
Net increase (decrease) in cash and cash equivalents	199	273,278
Cash and cash equivalents at beginning of period	19,275	33,889
Cash and cash equivalents at end of period	19,474	307,167
Noncash investing and financing activities:
Assumption of indebtedness and other liabilities in real estate acquisitions	76	50
Carrying amount of pre-existing ownership interest in acquired property	0	630
Conversion of Limited Partner Units to common shares	0	337
Subsidiary of Common Parent [Member]
Cash flows from operating activities:
Net income (loss)	25,571	44,123
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation of buildings and tenant improvements	71,393	70,548
Amortization of deferred leasing and other costs	26,871	29,232
Amortization of deferred financing costs	2,499	3,507
Straight-line rental income and expense, net	(5,974)	(4,839)
Gain on acquisitions	0	(962)
Gains on land and depreciated property sales	(30,106)	(9,122)
Third-party construction contracts, net	411	11,138
Other accrued revenues and expenses, net	(33,911)	(26,232)
Operating distributions received in excess of (less than) equity in earnings from unconsolidated companies	2,383	(43,930)
Net cash provided by operating activities	59,137	73,463
Cash flows from investing activities:
Development of real estate investments	(105,413)	(103,684)
Acquisition of real estate investments and related intangible assets	(17,224)	(35,495)
Acquisition of undeveloped land	(2,270)	(5,149)
Second generation tenant improvements, leasing costs and building improvements	(19,631)	(17,119)
Other deferred leasing costs	(8,706)	(11,079)
Other assets	5,539	(5,124)
Proceeds from land and depreciated property sales, net	70,673	61,931
Capital distributions from unconsolidated companies	2,546	89,237
Capital contributions and advances to unconsolidated companies	(420)	(4,846)
Net cash provided by (used for) investing activities	(74,906)	(31,328)
Cash flows from financing activities:
Contributions from the General Partner	23,783	574,685
Payments for redemption/repurchase of preferred shares/units	(17,656)	(177,955)
Proceeds from unsecured debt	0	250,000
Payments on unsecured debt	(511)	(480)
Proceeds from secured debt financings	0	1,933
Payments on secured indebtedness including principal amortization	(21,471)	(17,486)
Borrowings (payments) on line of credit, net	92,000	(285,000)
Distributions to common shareholders/unitholders	(56,342)	(55,458)
Distributions to preferred shareholders/unitholders	(7,140)	(9,550)
Distributions to Noncontrolling Interest, Net	(24)	(210)
Change in book overdrafts	3,629	(45,272)
Deferred financing costs	(300)	(4,064)
Net cash provided by (used for) financing activities	15,968	231,143
Net increase (decrease) in cash and cash equivalents	199	273,278
Cash and cash equivalents at beginning of period	19,275	33,889
Cash and cash equivalents at end of period	19,474	307,167
Noncash investing and financing activities:
Assumption of indebtedness and other liabilities in real estate acquisitions	76	50
Carrying amount of pre-existing ownership interest in acquired property	0	630
Conversion of Limited Partner Units to common shares	$ 0	$ 337