Debt - Narrative (Details)	6 Months Ended
	Jun. 30, 2019 USD ($) instrument extension	Dec. 31, 2018 USD ($)
Debt Instrument [Line Items]
Number of lines of unsecured credit (in instruments) | instrument	2
Unsecured Debt [Member]
Debt Instrument [Line Items]
Unamortized discount (premium), net	$ 9,200,000	$ 7,100,000
Unamortized debt issuance expense	21,500,000	18,500,000
Line of Credit [Member]
Debt Instrument [Line Items]
Aggregate borrowing capacity	1,240,000,000
Line of Credit [Member] | Unsecured Line of Credit [Member]
Debt Instrument [Line Items]
Unamortized debt issuance expense	4,400,000	3,900,000
Unsecured Line of Credit [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Aggregate borrowing capacity	$ 1,200,000,000
Number of extension options (in extensions) | extension	1
Extension period (in months)	18 months
Unsecured Line of Credit [Member] | Line of Credit [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Basis spread on variable rate	0.825%
Unsecured Line of Credit [Member] | Line of Credit Working Capital [Member]
Debt Instrument [Line Items]
Aggregate borrowing capacity	$ 35,000,000.0
Unsecured Line of Credit [Member] | Line of Credit Working Capital [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Basis spread on variable rate	0.825%
Mortgage notes payable, net [Member]
Debt Instrument [Line Items]
Unamortized discount (premium), net	$ (12,300,000)	(14,900,000)
Unamortized debt issuance expense	$ 3,400,000	$ 4,200,000