Fair Value Measurements - Financial Instruments at Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	$ 363,938	$ 361,746
Plainfield mortgage loan
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	19,027	19,295
Plainfield mortgage loan | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	19,441	20,240
Midland Mortgage Loan
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	105,600	105,600
Midland Mortgage Loan | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	107,894	107,154
AIG Loan
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	110,640	110,640
AIG Loan | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	118,521	114,747
Highway 94 mortgage loan
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	18,376	18,968
Highway 94 mortgage loan | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	17,476	17,658
Samsonite mortgage loan
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	23,984	24,561
Samsonite mortgage loan | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	25,323	26,044
HealthSpring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	22,260	0
HealthSpring | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	$ 22,541	$ 0