Debt - Schedule of Debt (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Oct. 22, 2015
Debt Instrument [Line Items]
Total Debt	$ 484,728	$ 484,728
Unamortized deferred financing costs	(2,606)	(2,880)
Total debt	482,122	481,848
Line of Credit | Key Bank Credit Facility
Debt Instrument [Line Items]
Total Debt	$ 357,758	357,758
Contractual interest rate	3.17%
Effective interest rate (percent)	3.65%
Notes Payable, Other Payables | AIG Loan
Debt Instrument [Line Items]
Total Debt	$ 126,970	$ 126,970
Total debt			$ 127,000
Contractual interest rate	4.15%		4.15%
Effective interest rate (percent)	4.22%