Consolidated Statements of Shareholders' Equity (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Consolidated Statements of Shareholders' Equity
Net unrealized loss from derivative instruments, tax benefit	$ (312)	$ 25	$ 275
Net unrealized loss from currency translation adjustment, tax benefit	$ 374	$ 300