Indebtedness - Summary of Indebtedness (Details) - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Mortgage Loans Payable, Net		$ 452,551	$ 495,956
Senior Unsecured Notes, Net		301,602	204,998
Unsecured Term Loans, Net		457,138	456,638
Unsecured Credit Facility		157,000	189,500
2017 Notes
Debt Instrument [Line Items]
Senior Unsecured Notes, Gross		$ 54,981	54,981
Interest Rate		7.50%
Effective Interest Rate		7.52%
Maturity Date		Dec. 01, 2017
2027 Notes
Debt Instrument [Line Items]
Senior Unsecured Notes, Gross		$ 6,070	6,070
Interest Rate		7.15%
Effective Interest Rate		7.11%
Maturity Date		May 15, 2027
2028 Notes
Debt Instrument [Line Items]
Senior Unsecured Notes, Gross		$ 31,901	31,901
Interest Rate		7.60%
Effective Interest Rate		8.13%
Maturity Date		Jul. 15, 2028
2032 Notes
Debt Instrument [Line Items]
Senior Unsecured Notes, Gross		$ 10,600	10,600
Interest Rate		7.75%
Effective Interest Rate		7.87%
Maturity Date		Apr. 15, 2032
2017 II Notes
Debt Instrument [Line Items]
Senior Unsecured Notes, Gross		$ 0	101,871
Maturity Date		May 15, 2017
2027 Private Placement Notes
Debt Instrument [Line Items]
Senior Unsecured Notes, Gross		$ 125,000	0
Interest Rate		4.30%
Effective Interest Rate		4.30%
Maturity Date		Apr. 20, 2027
2029 Private Placement Notes
Debt Instrument [Line Items]
Senior Unsecured Notes, Gross		$ 75,000	0
Interest Rate		4.40%
Effective Interest Rate		4.40%
Maturity Date		Apr. 20, 2029
2014 Unsecured Term Loan (A)
Debt Instrument [Line Items]
Unsecured Term Loans, Gross	[1]	$ 200,000	200,000
Interest Rate	[1]	3.99%
Maturity Date	[1]	Jan. 29, 2021
2015 Unsecured Term Loan (A)
Debt Instrument [Line Items]
Unsecured Term Loans, Gross	[1]	$ 260,000	260,000
Interest Rate	[1]	3.39%
Maturity Date	[1]	Sep. 12, 2022
Mortgage Loans Payable
Debt Instrument [Line Items]
Mortgage Loans Payable, Gross		$ 454,283	498,435
Unamortized Deferred Financing Costs		(2,033)	(2,905)
Unamortized Premiums		301	426
Mortgage Loans Payable, Net		$ 452,551	495,956
Maturity Date Range, Start		Jun. 01, 2018
Maturity Date Range, End		Sep. 01, 2022
Senior Unsecured Notes
Debt Instrument [Line Items]
Unamortized Deferred Financing Costs		$ (1,864)	(320)
Senior Unsecured Notes, Gross		303,552	205,423
Unamortized Discounts		86	105
Senior Unsecured Notes, Net		301,602	204,998
Unsecured Term Loan
Debt Instrument [Line Items]
Unamortized Deferred Financing Costs		(2,862)	(3,362)
Unsecured Term Loans, Gross		460,000	460,000
Unsecured Term Loans, Net		457,138	456,638
Unsecured Credit Facility
Debt Instrument [Line Items]
Unamortized Deferred Financing Costs		(1,881)	(2,876)
Unsecured Credit Facility	[2]	$ 157,000	$ 189,500
Interest Rate	[2]	2.39%
Maturity Date	[2]	Mar. 11, 2019
Minimum | Mortgage Loans Payable
Debt Instrument [Line Items]
Interest Rate		4.03%
Effective Interest Rate		3.82%
Maximum | Mortgage Loans Payable
Debt Instrument [Line Items]
Interest Rate		8.26%
Effective Interest Rate		8.26%

[1] The interest rate at September 30, 2017 reflects the interest rate protection agreements we entered into to effectively convert the variable rate to a fixed rate. See Note 10.

[2] The maturity date may be extended an additional year at our election, subject to certain restrictions. Amounts exclude unamortized deferred financing costs of $1,881 and $2,876 as of September 30, 2017 and December 31, 2016, respectively, which are included in prepaid expenses and other assets on the consolidated balance sheets.