Notes Payable to Trusts - Additional Information (Details)		1 Months Ended			12 Months Ended			60 Months Ended	61 Months Ended
	Jul. 27, 2010 USD ($)	Jul. 31, 2005 USD ($) Security	May 31, 2005 USD ($) Security	Apr. 30, 2005 USD ($) Security	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Jun. 30, 2010	Jul. 31, 2010	Jul. 11, 2011
Variable Interest Entity [Line Items]
Principal payments on notes payable to trusts					$ 88,662,000	$ 0	$ 0
Variable Interest Entity, Not Primary Beneficiary | Trust III
Variable Interest Entity [Line Items]
Proceeds from issuance of securities		$ 41,238,000
Variable Interest Entity, Not Primary Beneficiary | Trust III | Preferred Securities
Variable Interest Entity [Line Items]
Issuance of securities		40,000,000
Variable Interest Entity, Not Primary Beneficiary | Trust III | Common Securities
Variable Interest Entity [Line Items]
Issuance of securities		$ 1,238,000
Number of securities issued (in securities) | Security		1,238
Variable Interest Entity, Not Primary Beneficiary | Trust II
Variable Interest Entity [Line Items]
Proceeds from issuance of securities			$ 42,269,000
Variable Interest Entity, Not Primary Beneficiary | Trust II | Preferred Securities
Variable Interest Entity [Line Items]
Issuance of securities			41,000,000
Variable Interest Entity, Not Primary Beneficiary | Trust II | Common Securities
Variable Interest Entity [Line Items]
Issuance of securities			$ 1,269,000
Number of securities issued (in securities) | Security			1,269
Variable Interest Entity, Not Primary Beneficiary | Trust
Variable Interest Entity [Line Items]
Proceeds from issuance of securities				$ 36,083,000
Variable Interest Entity, Not Primary Beneficiary | Trust | Preferred Securities
Variable Interest Entity [Line Items]
Issuance of securities				35,000,000
Variable Interest Entity, Not Primary Beneficiary | Trust | Common Securities
Variable Interest Entity [Line Items]
Issuance of securities				$ 1,083,000
Number of securities issued (in securities) | Security				1,083
Operating Partnership | Variable Interest Entity, Not Primary Beneficiary | Trust III
Variable Interest Entity [Line Items]
Interest rate, fixed									6.91%
Interest rate swap, fixed interest rate										5.00%
Prepayment premium	$ 0
Operating Partnership | Variable Interest Entity, Not Primary Beneficiary | Trust III | LIBOR
Variable Interest Entity [Line Items]
Basis spread on variable rate					2.40%
Operating Partnership | Variable Interest Entity, Not Primary Beneficiary | Trust II
Variable Interest Entity [Line Items]
Interest rate, fixed								6.70%
Interest rate swap, fixed interest rate					5.00%
Prepayment premium					$ 0
Operating Partnership | Variable Interest Entity, Not Primary Beneficiary | Trust II | LIBOR
Variable Interest Entity [Line Items]
Basis spread on variable rate					2.40%
Operating Partnership | Variable Interest Entity, Not Primary Beneficiary | Trust
Variable Interest Entity [Line Items]
Interest rate swap, fixed interest rate					5.10%
Prepayment premium					$ 0
Operating Partnership | Variable Interest Entity, Not Primary Beneficiary | Trust | LIBOR
Variable Interest Entity [Line Items]
Basis spread on variable rate					2.30%
Notes payable to Trusts | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Principal payments on notes payable to trusts					$ 88,662,000
Unamortized deferred financing costs, net					0	$ 2,146,000
Notes payable to Trusts | Variable Interest Entity, Not Primary Beneficiary | Trust
Variable Interest Entity [Line Items]
Notes payable to Trusts					$ 30,928,000