RETIREMENT BENEFIT PLANS (Schedule of Change in Benefit Obligations and Plan Assets) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2015
Change In Projected Benefit Obligations
Projected benefit obligation, beginning of year	$ 668
Interest cost	95
Service cost	565
Actuarial loss	(12)
Employee contribution	180
Premiums paid	(89)
Benefit payment	(19)
Effect of foreign currency exchange rates	(175)
Projected benefit obligation, end of year	47,661
Change In Plan Assets
Plan assets at fair value, beginning of year	0
Actual return on plan assets	82
Employer contributions	450	$ 1,800
Employee contributions	180
Premiums paid	(89)
Effect of foreign currency exchange rates	(157)
Plan assets at fair value, end of year	26,943
Codman
Change In Projected Benefit Obligations
Transfer from Codman Neurosurgery acquisition	46,448
Change In Plan Assets
Transfer from Codman Neurosurgery acquisition	$ 26,477