Income Taxes - Schedule of Income Tax Expense (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Income Tax Expenses [Line Items]      
Federal income tax $ 0 $ 19 $ 0
Total income tax expense 394 965 601
State income tax      
Income Tax Expenses [Line Items]      
State income tax and built-in gain tax 394 899 601
REIT state built-in gain tax expense      
Income Tax Expenses [Line Items]      
State income tax and built-in gain tax $ 0 $ 47 $ 0