Employee Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2017

Defined Contribution Plan [Abstract]

Matching contributions [Table Text Block]

The table below sets forth our contributions for the past three years (in thousands):

	2017		2016		2015
Defined contribution and international retirement plans	$	6,946	$	5,817	$	5,583
Deferred compensation plan	325		194		218