Indebtedness - Additional Information (Details) $ in Thousands, ft² in Millions				12 Months Ended
		Sep. 11, 2015 USD ($)	Jan. 29, 2014 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($) ft² Property	Dec. 31, 2017 USD ($)
Debt Instrument [Line Items]
Loss from Retirement of Debt				$ 0	$ (39)	$ (1,775)
Long-term Debt, Gross				$ 1,490,931
2029 II Private Placement Notes
Debt Instrument [Line Items]
Interest Rate				3.97%
Long-term Debt, Gross				$ 150,000	0
Effective Interest Rate				4.23%
2028 Private Placement Notes
Debt Instrument [Line Items]
Interest Rate				3.86%
Long-term Debt, Gross				$ 150,000	$ 150,000
Effective Interest Rate				3.86%	3.86%
2030 Private Placement Notes
Debt Instrument [Line Items]
Interest Rate				3.96%
Long-term Debt, Gross				$ 150,000	$ 150,000
Effective Interest Rate				3.96%	3.96%
2027 Private Placement Notes
Debt Instrument [Line Items]
Interest Rate				4.30%
Long-term Debt, Gross				$ 125,000	$ 125,000	$ 125,000
Effective Interest Rate				4.30%		4.30%
2029 Private Placement Notes
Debt Instrument [Line Items]
Interest Rate				4.40%
Long-term Debt, Gross				$ 75,000	75,000	$ 75,000
Effective Interest Rate				4.40%		4.40%
2014 Unsecured Term Loan (A)
Debt Instrument [Line Items]
Loss from Retirement of Debt						$ 51
Interest Rate	[1]			3.39%
Debt Instrument, term			7 years
Long-term Debt, Gross				$ 200,000	$ 200,000
Unsecured term loan, face amount			$ 200,000
Debt instrument, interest rate terms					LIBOR plus 110 basis points
2015 Unsecured Term Loan (A)
Debt Instrument [Line Items]
Interest Rate	[1]			2.89%
Debt Instrument, term		7 years
Long-term Debt, Gross				$ 260,000	$ 260,000
Unsecured term loan, face amount		$ 260,000
Debt instrument, interest rate terms					LIBOR plus 110 basis points
Mortgage Loans Payable
Debt Instrument [Line Items]
Unamortized Debt Issuance Expense				675	$ 1,246
Extinguishment of debt, amount				117,199	157,782
Loss from Retirement of Debt					39	1,653
Net carrying value of industrial properties collateralized by mortgage loans				264,956
Long-term Debt, Gross				174,360	297,610
Mortgage Loans Payable | Assumed Mortgage
Debt Instrument [Line Items]
Assumed mortgage loan					$ 11,654
Number of industrial properties acquired | Property					3
Gross leasable area (GLA) of industrial properties acquired | ft²					0.2
Interest Rate					4.17%
Debt Instrument, term					30 years
Unsecured Credit Facility
Debt Instrument [Line Items]
Unamortized Debt Issuance Expense				$ 2,300	$ 3,554
Loss from Retirement of Debt						$ 71
Interest Rate				2.90%
Line of Credit Facility, current borrowing capacity				$ 725,000
Line of Credit Facility, additional borrowings capacity				$ 1,000,000
Number of years of extension of the Line of Credit Facility at election				1 year
Line of Credit Facility, interest rate description				LIBOR plus 110 basis points

[1] See Note 12.