Debt - Schedule of Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Feb. 01, 2016
Debt Instrument [Line Items]
Principal Amount	$ 565,000	$ 455,000
Deferred Loan Fees	(6,088)	(5,284)
Carrying Value	558,912	449,716
Senior unsecured notes payable
Debt Instrument [Line Items]
Principal Amount	300,000	260,000
Deferred Loan Fees	(5,605)	(4,706)
Carrying Value	294,395	255,294
Senior unsecured term loan
Debt Instrument [Line Items]
Principal Amount	100,000	100,000	$ 100,000
Deferred Loan Fees	(483)	(578)
Carrying Value	99,517	99,422
Unsecured revolving credit facility
Debt Instrument [Line Items]
Principal Amount	165,000	95,000
Deferred Loan Fees	0	0
Carrying Value	$ 165,000	$ 95,000