Indebtedness - Additional Information (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 1,651,674
Unsecured Credit Facility
Debt Instrument [Line Items]
Unamortized Debt Issuance Costs		$ 1,986	$ 2,300
Interest Rate	[1]	2.09%
Maturity Date	[2]	Oct. 29, 2021
Mortgage Loans Payable
Debt Instrument [Line Items]
Unamortized Debt Issuance Costs		$ 593	675
Net carrying value of industrial properties collateralized by mortgage loans		262,852
Long-term Debt, Gross		173,103	174,360
2014 Unsecured Term Loan
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 200,000	200,000
Interest Rate	[1]	3.39%
Maturity Date	[1]	Jan. 29, 2021
2015 Unsecured Term Loan
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 260,000	260,000
Interest Rate	[1]	2.89%
Maturity Date	[1]	Sep. 12, 2022
2028 Private Placement Notes
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 150,000	150,000
Interest Rate		3.86%
Effective Interest Rate		3.86%
Maturity Date		Feb. 15, 2028
2029 II Private Placement Notes
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 150,000	150,000
Interest Rate		3.97%
Effective Interest Rate		4.23%
Maturity Date		Jul. 23, 2029
2030 Private Placement Notes
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 150,000	$ 150,000
Interest Rate		3.96%
Effective Interest Rate		3.96%
Maturity Date		Feb. 15, 2030

[1] The interest rate at March 31, 2020 also reflects the derivative instruments 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 debt issuance costs of $1,986 and $2,300 as of March 31, 2020 and December 31, 2019, respectively, which are included in the line item Prepaid Expenses and Other Assets, Net.