Debt - Credit Facility (Details)	Feb. 20, 2018 USD ($)
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 300,000,000.0
Unsecured Debt | Senior Unsecured Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity	500,000,000.0
Unsecured Debt | Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 150,000,000.0
Basis spread on variable rate	1.35%
Unsecured Debt | $300 Million Term Loan
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 350,000,000.0
Basis spread on variable rate	1.25%
Unsecured Debt | $150 Million Term Loan
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 150,000,000.0
Other Secured Financings
Debt Instrument [Line Items]
Maximum borrowing capacity	40,400,000.0
Core Portfolio | Unsecured Debt | Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity	150,000,000.0
Core Portfolio | Unsecured Debt | $150 Million Term Loan
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 150,000,000.0