Guarantor and Non-Guarantor Financial Information - Condensed Consolidated Statements of Cash Flows (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided by Operating Activities	$ 111,662	$ 102,744
Cash Flows from Investing Activities:
Investment in real estate assets, consolidated joint venture, and real estate related intangibles, net of accruals	(58,320)	(64,422)
Intercompany note receivable		0
Net sales proceeds from wholly-owned properties	23,023	201,690
Investments in unconsolidated joint ventures	(284)	0
Deferred lease costs paid	(9,563)	(6,266)
Net cash (used in)/provided by investing activities	(45,144)	131,002
Cash Flows from Financing Activities:
Debt issuance costs paid	(102)	(138)
Proceeds from debt	147,000	211,000
Repayments of debt	(115,694)	(357,597)
Intercompany note payable		0
Costs of issuance of common stock	(74)	(42)
Shares withheld to pay tax obligations related to employee stock compensation	(3,380)	(2,283)
Repurchases of common stock as part of announced plan	0	(7,943)
(Distributions to)/repayments from affiliates	0	0
Dividends paid and discount on dividend reinvestments	(91,664)	(61,075)
Net cash used in financing activities	(63,914)	(218,078)
Net increase in cash and cash equivalents	2,604	15,668
Cash and cash equivalents, beginning of period	6,992	5,441
Cash and cash equivalents, end of period	9,596	21,109
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided by Operating Activities	0	19,628
Cash Flows from Investing Activities:
Investment in real estate assets, consolidated joint venture, and real estate related intangibles, net of accruals	0	0
Intercompany note receivable		(9,600)
Net sales proceeds from wholly-owned properties	0	0
Investments in unconsolidated joint ventures	0
Deferred lease costs paid	0	0
Net cash (used in)/provided by investing activities	0	(9,600)
Cash Flows from Financing Activities:
Debt issuance costs paid	0	0
Proceeds from debt	0	0
Repayments of debt	0	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	0	(19,628)
Dividends paid and discount on dividend reinvestments	0	0
Net cash used in financing activities	0	(10,028)
Net increase in cash and cash equivalents	0	0
Cash and cash equivalents, beginning of period	0	0
Cash and cash equivalents, end of period	0	0
Issuer [Member]
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided by Operating Activities	(10,028)	(14,105)
Cash Flows from Investing Activities:
Investment in real estate assets, consolidated joint venture, and real estate related intangibles, net of accruals	(757)	(13,062)
Intercompany note receivable		0
Net sales proceeds from wholly-owned properties	23,032	108,550
Investments in unconsolidated joint ventures	(284)
Deferred lease costs paid	(736)	(1,712)
Net cash (used in)/provided by investing activities	21,255	93,776
Cash Flows from Financing Activities:
Debt issuance costs paid	(102)	(138)
Proceeds from debt	147,000	211,000
Repayments of debt	(115,000)	(232,000)
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	(41,618)	(34,837)
Dividends paid and discount on dividend reinvestments	0	0
Net cash used in financing activities	(9,720)	(65,575)
Net increase in cash and cash equivalents	1,507	14,096
Cash and cash equivalents, beginning of period	3,674	2,174
Cash and cash equivalents, end of period	5,181	16,270
Guarantor [Member]
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided by Operating Activities	3,091	3,075
Cash Flows from Investing Activities:
Investment in real estate assets, consolidated joint venture, and real estate related intangibles, net of accruals	0	0
Intercompany note receivable		0
Net sales proceeds from wholly-owned properties	0	0
Investments in unconsolidated joint ventures	0
Deferred lease costs paid	0	0
Net cash (used in)/provided by 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	(74)	(42)
Shares withheld to pay tax obligations related to employee stock compensation	(3,380)	(2,283)
Repurchases of common stock as part of announced plan		(7,943)
(Distributions to)/repayments from affiliates	92,020	68,259
Dividends paid and discount on dividend reinvestments	(91,657)	(61,066)
Net cash used in financing activities	(3,091)	(3,075)
Net increase in cash and cash equivalents	0	0
Cash and cash equivalents, beginning of period	150	150
Cash and cash equivalents, end of period	150	150
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided by Operating Activities	118,599	94,146
Cash Flows from Investing Activities:
Investment in real estate assets, consolidated joint venture, and real estate related intangibles, net of accruals	(57,563)	(51,360)
Intercompany note receivable		9,600
Net sales proceeds from wholly-owned properties	(9)	93,140
Investments in unconsolidated joint ventures	0
Deferred lease costs paid	(8,827)	(4,554)
Net cash (used in)/provided by investing activities	(66,399)	46,826
Cash Flows from Financing Activities:
Debt issuance costs paid	0	0
Proceeds from debt	0	0
Repayments of debt	(694)	(125,597)
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	(50,402)	(13,794)
Dividends paid and discount on dividend reinvestments	(7)	(9)
Net cash used in financing activities	(51,103)	(139,400)
Net increase in cash and cash equivalents	1,097	1,572
Cash and cash equivalents, beginning of period	3,168	3,117
Cash and cash equivalents, end of period	$ 4,265	$ 4,689