Derivative Instruments - Changes in AOCI (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Ending balance	[1]	$ (34,599)
Balance as of December 31, 2018	[1]	(34,599)	$ (40,501)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		37
Net unrealized gain on cash flow hedges		4
Reclassification of net realized gain on cash flow hedges into current operations		(41)
Ending balance		0
Balance as of December 31, 2018		$ 37	$ 0

[1] Prior period amounts have been adjusted to reflect the two-for-one stock split effected in the form of a stock dividend