Accrued Liabilities - Carrying Value of Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Accrued Liabilities and Other Liabilities [Abstract]
Wages, severance and related taxes	$ 58,953	$ 46,674
Current deferred revenue	54,255	62,272
Accrued rebates	37,170	41,312
Accrued interest	18,781	18,530
Employee benefits	17,791	17,984
Lease liabilities	14,072	0
Other (individual items less than 5% of total current liabilities)	82,777	85,624
Accrued liabilities	$ 283,799	$ 272,396