Unconsolidated Affiliates and Noncontrolling Interests - Variable Interest Entities (Details) $ in Thousands	Sep. 30, 2019 USD ($)
Ambassador Infrastructure, LLC
Noncontrolling Interest [Line Items]
Investment in Real Estate Joint Ventures and Partnerships	$ 0
Maximum Risk of Loss	10,050
Bullseye, LLC
Noncontrolling Interest [Line Items]
Investment in Real Estate Joint Ventures and Partnerships	5
Maximum Risk of Loss	5
Continental 425 Fund LLC
Noncontrolling Interest [Line Items]
Investment in Real Estate Joint Ventures and Partnerships	7,243
Maximum Risk of Loss	7,243
EastGate Storage, LLC
Noncontrolling Interest [Line Items]
Investment in Real Estate Joint Ventures and Partnerships	885
Maximum Risk of Loss	3,250
Hamilton Place Self Storage, LLC
Noncontrolling Interest [Line Items]
Investment in Real Estate Joint Ventures and Partnerships	1,463
Maximum Risk of Loss	7,002
Parkdale Self Storage, LLC
Noncontrolling Interest [Line Items]
Investment in Real Estate Joint Ventures and Partnerships	1,190
Maximum Risk of Loss	6,500
Self-Storage at Mid Rivers, LLC
Noncontrolling Interest [Line Items]
Investment in Real Estate Joint Ventures and Partnerships	844
Maximum Risk of Loss	2,994
Shoppes at Eagle Point, LLC
Noncontrolling Interest [Line Items]
Investment in Real Estate Joint Ventures and Partnerships	16,268
Maximum Risk of Loss	$ 16,268