Indebtedness - Additional Information (Details) - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 1,417,663
Unsecured Credit Facility
Debt Instrument [Line Items]
Unamortized Debt Issuance Costs		$ 2,613	$ 3,554
Interest Rate	[1]	3.14%
Maturity Date	[2]	Oct. 29, 2021
Mortgage Loans Payable
Debt Instrument [Line Items]
Unamortized Debt Issuance Costs		$ 779	1,246
Extinguishment of debt, amount		111,761
Net carrying value of industrial properties collateralized by mortgage loans		280,649
Long-term Debt, Gross		181,092	297,610
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	0
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 September 30, 2019 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 $2,613 and $3,554 as of September 30, 2019 and December 31, 2018, respectively, which are included in the line item Prepaid Expenses and Other Assets, Net.