Significant Accounting Policies (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Jan. 01, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Stock-based compensation expense	$ 290	$ 832
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accumulated other comprehensive loss	(98,889)			$ (105,172)
Retained earnings (accumulated deficit)	$ (166,446)			$ (161,165)
Accounting Standards Update 2017-12
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accumulated other comprehensive loss			$ (300)
Retained earnings (accumulated deficit)			$ 300