Restructuring Charge (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Summary of the changes in accrued restructuring charge
Balance, beginning of year	$ 3,855	$ 2,600	$ 694
Restructuring charge	1,699	8,506	12,374
Cash paid	(4,150)	(4,667)	(5,957)
Non-cash items	196	(2,584)	(4,511)
Balance, end of year	$ 1,600	$ 3,855	$ 2,600