Guarantor and Non-Guarantor Financial Information - Condensed Consolidated Statements of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided by Operating Activities	$ 49,708	$ 43,806
Cash Flows from Investing Activities:
Investment in real estate assets and real estate related intangibles, net of accruals	(26,537)	(81,358)
Redemption of noncontrolling interest in unconsolidated variable interest entity	0	(4,000)
Intercompany note receivable	0
Net sales proceeds from wholly-owned properties	45,400	25,803
Deferred lease costs paid	(2,860)	(4,414)
Net cash provided by/(used in) investing activities	16,003	(63,969)
Cash Flows from Financing Activities:
Debt issuance costs paid	(99)	(242)
Proceeds from debt	178,000	257,575
Repayments of debt	(205,262)	(209,254)
Intercompany note payable	0
Costs of issuance of common stock	(42)	(90)
Shares withheld to pay tax obligations related to employee stock compensation	(541)	(176)
Repurchases of common stock as part of announced plan	(7,943)	0
(Distributions to)/repayments from affiliates	0	0
Dividends paid and discount on dividend reinvestments	(30,533)	(32,477)
Net cash (used in)/provided by financing activities	(66,420)	15,336
Net decrease in cash and cash equivalents	(709)	(4,827)
Cash and cash equivalents, end of period	4,732	7,479
Cash and cash equivalents, beginning of period	5,441	12,306
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided by Operating Activities	9,490	7,835
Cash Flows from Investing Activities:
Investment in real estate assets and real estate related intangibles, net of accruals	0	0
Redemption of noncontrolling interest in unconsolidated variable interest entity		0
Intercompany note receivable	(9,600)
Net sales proceeds from wholly-owned properties	0	0
Deferred lease costs paid	0	0
Net cash provided by/(used in) investing activities	(9,600)	0
Cash Flows from Financing Activities:
Debt issuance costs paid	0	0
Proceeds from debt	$ 0	0
Repayments of debt		0
Intercompany note payable	$ 9,600
Costs of issuance of common stock	0	0
Shares withheld to pay tax obligations related to employee stock compensation	0	0
Repurchases of common stock as part of announced plan	0
(Distributions to)/repayments from affiliates	(9,490)	(7,835)
Dividends paid and discount on dividend reinvestments	0	0
Net cash (used in)/provided by financing activities	110	(7,835)
Net decrease in cash and cash equivalents	0	0
Cash and cash equivalents, end of period	0	0
Cash and cash equivalents, beginning of period	0	0
Issuer [Member]
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided by Operating Activities	(10,726)	(6,974)
Cash Flows from Investing Activities:
Investment in real estate assets and real estate related intangibles, net of accruals	(833)	(5,091)
Redemption of noncontrolling interest in unconsolidated variable interest entity		0
Intercompany note receivable	0
Net sales proceeds from wholly-owned properties	45,400	25,803
Deferred lease costs paid	(1,044)	(846)
Net cash provided by/(used in) investing activities	43,523	19,866
Cash Flows from Financing Activities:
Debt issuance costs paid	(99)	(242)
Proceeds from debt	178,000	257,575
Repayments of debt	(80,000)	(209,000)
Intercompany note payable	(9,600)
Costs of issuance of common stock	0	0
Shares withheld to pay tax obligations related to employee stock compensation	0	0
Repurchases of common stock as part of announced plan	0
(Distributions to)/repayments from affiliates	(121,791)	(65,489)
Dividends paid and discount on dividend reinvestments	0	0
Net cash (used in)/provided by financing activities	(33,490)	(17,156)
Net decrease in cash and cash equivalents	(693)	(4,264)
Cash and cash equivalents, end of period	1,481	3,879
Cash and cash equivalents, beginning of period	2,174	8,143
Guarantor [Member]
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided by Operating Activities	679	602
Cash Flows from Investing Activities:
Investment in real estate assets and real estate related intangibles, net of accruals	0	0
Redemption of noncontrolling interest in unconsolidated variable interest entity		0
Intercompany note receivable	0
Net sales proceeds from wholly-owned properties	0	0
Deferred lease costs paid	0	0
Net cash provided by/(used in) investing activities	0	0
Cash Flows from Financing Activities:
Debt issuance costs paid	0	0
Proceeds from debt	0	0
Repayments of debt	0	0
Intercompany note payable	0
Costs of issuance of common stock	(42)	(90)
Shares withheld to pay tax obligations related to employee stock compensation	(541)	(176)
Repurchases of common stock as part of announced plan	(7,943)
(Distributions to)/repayments from affiliates	38,380	30,601
Dividends paid and discount on dividend reinvestments	(30,533)	(32,477)
Net cash (used in)/provided by financing activities	(679)	(2,142)
Net decrease in cash and cash equivalents	0	(1,540)
Cash and cash equivalents, end of period	150	250
Cash and cash equivalents, beginning of period	150	1,790
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided by Operating Activities	50,265	42,343
Cash Flows from Investing Activities:
Investment in real estate assets and real estate related intangibles, net of accruals	(25,704)	(76,267)
Redemption of noncontrolling interest in unconsolidated variable interest entity		(4,000)
Intercompany note receivable	9,600
Net sales proceeds from wholly-owned properties	0	0
Deferred lease costs paid	(1,816)	(3,568)
Net cash provided by/(used in) investing activities	(17,920)	(83,835)
Cash Flows from Financing Activities:
Debt issuance costs paid	0	0
Proceeds from debt	0	0
Repayments of debt	(125,262)	(254)
Intercompany note payable	0
Costs of issuance of common stock	0	0
Shares withheld to pay tax obligations related to employee stock compensation	0	0
Repurchases of common stock as part of announced plan	0
(Distributions to)/repayments from affiliates	92,901	42,723
Dividends paid and discount on dividend reinvestments	0	0
Net cash (used in)/provided by financing activities	(32,361)	42,469
Net decrease in cash and cash equivalents	(16)	977
Cash and cash equivalents, end of period	3,101	3,350
Cash and cash equivalents, beginning of period	$ 3,117	$ 2,373