Guarantor Financials Guarantor and Non-Guarantor Financial Information - Condensed Consolidated Statements of Cash Flows (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided by Operating Activities	$ 215,079	$ 220,925	$ 267,095
Cash Flows from Investing Activities:
Acquisition of real estate assets, related intangibles and capitalized expenditures, net of accruals	(542,170)	(108,487)	(215,609)
Intercompany note receivable	0	0	0
Cash assumed upon consolidation of variable interest entity	0	0	5,063
Acquisition of unconsolidated joint ventures, net of cash assumed	(14,242)	0	0
Net sale proceeds from wholly-owned properties and consolidated joint venture	95,671	93,839	291,785
Net sale proceeds received from unconsolidated joint ventures	0	0	3,036
Investments in unconsolidated joint ventures	(793)	(136)	(151)
Liquidation of noncontrolling interest upon sale of consolidated joint venture	0	0	(95)
Deferred lease costs paid	(34,298)	(48,692)	(47,049)
Net cash provided/(used in) by investing activities	(495,832)	(63,476)	36,980
Cash Flows from Financing Activities:
Deferred financing costs paid	(4,892)	(3,125)	(3,367)
Proceeds from debt	1,085,604	409,000	829,000
Repayments of debt	(500,000)	(465,000)	(822,875)
Intercompany note payable	0	0	0
Net costs of issuance of common stock	(91)	(229)	(252)
Repurchases of common stock as part of announced plan	(173,551)	(88,450)	(3,244)
Intercompany distributions	0	0	0
Dividends paid and discount on dividend reinvestments	(132,301)	(136,378)	(220,365)
Net cash provided by/(used in) financing activities	274,769	(284,182)	(221,103)
Net increase/(decrease) in cash and cash equivalents	(5,984)	(126,733)	82,972
Cash and cash equivalents, beginning of year	12,957	139,690	56,718
Cash and cash equivalents, end of year	6,973	12,957	139,690
Issuer [Member]
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided by Operating Activities	15,327	32,260	34,362
Cash Flows from Investing Activities:
Acquisition of real estate assets, related intangibles and capitalized expenditures, net of accruals	(10,382)	(20,763)	(15,856)
Intercompany note receivable	0	0	0
Cash assumed upon consolidation of variable interest entity			0
Acquisition of unconsolidated joint ventures, net of cash assumed	18,045
Net sale proceeds from wholly-owned properties and consolidated joint venture	50,118	93,839	31,704
Net sale proceeds received from unconsolidated joint ventures			3,036
Investments in unconsolidated joint ventures	(793)	(136)	(151)
Liquidation of noncontrolling interest upon sale of consolidated joint venture			0
Deferred lease costs paid	(10,980)	(4,164)	(10,695)
Net cash provided/(used in) by investing activities	46,008	68,776	8,038
Cash Flows from Financing Activities:
Deferred financing costs paid	(4,892)	(3,125)	(2,717)
Proceeds from debt	1,085,604	409,000	829,000
Repayments of debt	(500,000)	(280,000)	(779,000)
Intercompany note payable	0	0	(53,000)
Net costs of issuance of common stock	0	0	0
Repurchases of common stock as part of announced plan	0	0	0
Intercompany distributions	(701,066)	(331,460)	68,721
Dividends paid and discount on dividend reinvestments	0	0	0
Net cash provided by/(used in) financing activities	(120,354)	(205,585)	63,004
Net increase/(decrease) in cash and cash equivalents	(59,019)	(104,549)	105,404
Cash and cash equivalents, beginning of year	62,371	166,920	61,516
Cash and cash equivalents, end of year	3,352	62,371	166,920
Guarantor [Member]
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided by Operating Activities	1,853	2,215	2,375
Cash Flows from Investing Activities:
Acquisition of real estate assets, related intangibles and capitalized expenditures, net of accruals	0	0	0
Intercompany note receivable	500	(2,500)	0
Cash assumed upon consolidation of variable interest entity			0
Acquisition of unconsolidated joint ventures, net of cash assumed	0
Net sale proceeds from wholly-owned properties and consolidated joint venture	0	0	0
Net sale proceeds received from unconsolidated joint ventures			0
Investments in unconsolidated joint ventures	0	0	0
Liquidation of noncontrolling interest upon sale of consolidated joint venture			0
Deferred lease costs paid	0	0	0
Net cash provided/(used in) by investing activities	500	(2,500)	0
Cash Flows from Financing Activities:
Deferred financing costs paid	0	0	0
Proceeds from debt	0	0	0
Repayments of debt	0	0	0
Intercompany note payable	0	0	0
Net costs of issuance of common stock	(91)	(229)	(252)
Repurchases of common stock as part of announced plan	(173,551)	(88,450)	(3,244)
Intercompany distributions	303,486	225,427	218,322
Dividends paid and discount on dividend reinvestments	(132,286)	(136,363)	(217,958)
Net cash provided by/(used in) financing activities	(2,442)	385	(3,132)
Net increase/(decrease) in cash and cash equivalents	(89)	100	(757)
Cash and cash equivalents, beginning of year	239	139	896
Cash and cash equivalents, end of year	150	239	139
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided by Operating Activities	172,992	162,800	204,913
Cash Flows from Investing Activities:
Acquisition of real estate assets, related intangibles and capitalized expenditures, net of accruals	(532,088)	(87,724)	(199,753)
Intercompany note receivable	0	0	53,000
Cash assumed upon consolidation of variable interest entity			5,063
Acquisition of unconsolidated joint ventures, net of cash assumed	(32,287)
Net sale proceeds from wholly-owned properties and consolidated joint venture	45,553	0	260,081
Net sale proceeds received from unconsolidated joint ventures			0
Investments in unconsolidated joint ventures	0	0	0
Liquidation of noncontrolling interest upon sale of consolidated joint venture			(95)
Deferred lease costs paid	(23,318)	(44,528)	(36,354)
Net cash provided/(used in) by investing activities	(542,140)	(132,252)	81,942
Cash Flows from Financing Activities:
Deferred financing costs paid	0	0	(650)
Proceeds from debt	0	0	0
Repayments of debt	0	(185,000)	(43,875)
Intercompany note payable	(500)	2,500	0
Net costs of issuance of common stock	0	0	0
Repurchases of common stock as part of announced plan	0	0	0
Intercompany distributions	422,787	129,683	(261,598)
Dividends paid and discount on dividend reinvestments	(15)	(15)	(2,407)
Net cash provided by/(used in) financing activities	422,272	(52,832)	(308,530)
Net increase/(decrease) in cash and cash equivalents	53,124	(22,284)	(21,675)
Cash and cash equivalents, beginning of year	(49,653)	(27,369)	(5,694)
Cash and cash equivalents, end of year	3,471	(49,653)	(27,369)
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided by Operating Activities	24,907	23,650	25,445
Cash Flows from Investing Activities:
Acquisition of real estate assets, related intangibles and capitalized expenditures, net of accruals	300	0	0
Intercompany note receivable	(500)	2,500	(53,000)
Cash assumed upon consolidation of variable interest entity			0
Acquisition of unconsolidated joint ventures, net of cash assumed	0
Net sale proceeds from wholly-owned properties and consolidated joint venture	0	0	0
Net sale proceeds received from unconsolidated joint ventures			0
Investments in unconsolidated joint ventures	0	0	0
Liquidation of noncontrolling interest upon sale of consolidated joint venture			0
Deferred lease costs paid	0	0	0
Net cash provided/(used in) by investing activities	(200)	2,500	(53,000)
Cash Flows from Financing Activities:
Deferred financing costs paid	0	0	0
Proceeds from debt	0	0	0
Repayments of debt	0	0	0
Intercompany note payable	500	(2,500)	53,000
Net costs of issuance of common stock	0	0	0
Repurchases of common stock as part of announced plan	0	0	0
Intercompany distributions	(25,207)	(23,650)	(25,445)
Dividends paid and discount on dividend reinvestments	0	0	0
Net cash provided by/(used in) financing activities	(24,707)	(26,150)	27,555
Net increase/(decrease) in cash and cash equivalents	0	0	0
Cash and cash equivalents, beginning of year	0	0	0
Cash and cash equivalents, end of year	$ 0	$ 0	$ 0