Quarterly Financial Information (Unaudited) - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended																				12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Net income/(loss)	$ 7,184	$ 6,256	$ 10,450	$ 11,054	$ 13,848	$ 10,675	$ 13,125	$ 11,669													$ 34,944	$ 49,317	$ 37,187
Restatement Adjustment
Business Acquisition [Line Items]
Net income/(loss)					$ (800)	$ (100)	$ (100)	$ (100)	$ (100)	$ (100)	$ (100)	$ (100)	$ (100)	$ (100)	$ (100)	$ (100)	$ (100)	$ (100)	$ (100)	$ (100)