CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash Flows from Operating Activities:
Net income		$ 99,717	$ 131,319	$ 42,165
Operating distributions received from unconsolidated joint ventures		579	774	266
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation		127,733	134,503	138,679
Amortization of debt issuance costs		1,702	1,768	1,578
Gain/(loss) on settlement of forward starting interest rate swaps		0	(1,284)	14,960
Other amortization		74,373	61,221	56,327
Impairment loss on real estate assets	[1]	33,901	43,301	0
Stock compensation expense		7,928	8,789	5,250
Equity in loss/(income) of unconsolidated joint ventures		(362)	(553)	350
Gain on sale of real estate assets, net		(93,410)	(129,683)	(1,132)
Retirement of shares returned from escrow		0	0	(1,479)
Changes in assets and liabilities:
Increase in tenant and straight-line rent receivables, net		(26,747)	(29,478)	(40,505)
Decrease/(increase) in restricted cash and escrows		3,229	(5,256)	(135)
Decrease/(increase) in prepaid expenses and other assets		1,996	(828)	(1,884)
Increase/(decrease) in accounts payable and accrued expenses		3,729	(162)	2,995
Increase/(decrease) in deferred income		1,441	4,613	(277)
Net cash provided by operating activities		235,809	219,044	217,158
Cash Flows from Investing Activities:
Acquisition of real estate assets, net of related debt assumed, and intangibles		(349,668)	(382,773)	(117,418)
Net cash held in escrow for acquisitions		0	0	(5,150)
Capitalized expenditures, net of accruals		(110,228)	(118,671)	(168,891)
Redemption of noncontrolling interest in unconsolidated variable interest entity		0	(4,000)	0
Net sale proceeds from wholly-owned properties		365,918	848,169	46,232
Net sale proceeds received from unconsolidated joint ventures		0	0	6,017
Investments in unconsolidated joint ventures		0	0	(42)
Deferred lease costs paid		(25,896)	(37,683)	(27,694)
Net cash provided by/(used in) investing activities		(119,874)	305,042	(266,946)
Cash Flows from Financing Activities:
Debt issuance costs paid		(264)	(1,081)	(1,294)
Proceeds from debt		695,000	1,301,858	1,052,527
Repayments of debt		(706,875)	(1,544,301)	(813,702)
Discount paid due to loan modification		0	0	(1,135)
Costs of issuance of common stock		(342)	(326)	0
Shares withheld to pay tax obligations related to employee stock compensation		(2,344)	(1,710)	(1,275)
Repurchases of common stock as part of announced plan		(7,943)	(158,860)	(54,802)
Dividends paid and discount on dividend reinvestments		(91,616)	(126,531)	(125,198)
Net cash provided by/(used in) financing activities		(114,384)	(530,951)	55,121
Net increase/(decrease) in cash and cash equivalents		1,551	(6,865)	5,333
Cash and cash equivalents, beginning of year		5,441	12,306	6,973
Cash and cash equivalents, end of year		$ 6,992	$ 5,441	$ 12,306

[1] The fair value measurements used in the evaluation of the non-financial assets above are considered to be Level 1 valuations within the fair value hierarchy as defined by GAAP, as there are direct observations and transactions involving the assets by unrelated, third-party purchasers.