Segment Reporting - Segment Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Segment Reporting Information, Additional Information
Assets	$ 4,646,116	$ 4,698,923
Operating Segments | Net Lease
Segment Reporting Information, Additional Information
Assets	3,988,468	3,905,402
Operating Segments | All Other
Segment Reporting Information, Additional Information
Assets	277,969	266,231
Operating Segments | Self Storage
Segment Reporting Information, Additional Information
Assets	243,531	252,195
Corporate
Segment Reporting Information, Additional Information
Assets	$ 136,148	$ 275,095