Indebtedness - Additional Information (Details) - USD ($) $ in Thousands		6 Months Ended
		Jun. 30, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 1,635,425
Unsecured Credit Facility
Debt Instrument [Line Items]
Unamortized Debt Issuance Costs		$ 1,684	$ 2,300
Interest Rate	[1]	1.39%
Maturity Date	[2]	Oct. 29, 2021
Mortgage Loans Payable
Debt Instrument [Line Items]
Unamortized Debt Issuance Costs		$ 511	675
Extinguishment of Debt, Amount		15,115
Net carrying value of industrial properties collateralized by mortgage loans		239,908
Long-term Debt, Gross		156,854	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 June 30, 2020 also reflects the derivative instruments we entered into to effectively convert the variable rate to a fixed rate. See Note 10. Additionally, on July 15, 2020 the 2014 Unsecured Term Loan was repaid. See Note 13.

[2] The maturity date may be extended an additional year at our election, subject to certain restrictions. Amounts exclude unamortized debt issuance costs of $1,684 and $2,300 as of June 30, 2020 and December 31, 2019, respectively, which are included in the line item Prepaid Expenses and Other Assets, Net. The interest rate at June 30, 2020 also reflects the derivative instrument we entered into to effectively convert a portion of the variable rate into a fixed rate. See Note 10.