Debt - Schedule of Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Principal Amount	$ 495,000	$ 455,000
Deferred Loan Fees	(6,286)	(5,284)
Carrying Value	488,714	449,716
Senior unsecured notes payable
Debt Instrument [Line Items]
Principal Amount	300,000	260,000
Deferred Loan Fees	(5,779)	(4,706)
Carrying Value	294,221	255,294
Senior unsecured term loan
Debt Instrument [Line Items]
Principal Amount	100,000	100,000
Deferred Loan Fees	(507)	(578)
Carrying Value	99,493	99,422
Unsecured revolving credit facility
Debt Instrument [Line Items]
Principal Amount	95,000	95,000
Deferred Loan Fees	0	0
Carrying Value	$ 95,000	$ 95,000