Supplemental balance sheet and cash flow information (other non-current assets, accrued liabilities) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Dec. 31, 2019
Other non-current assets
Postretirement benefit plan asset				$ 58,130	$ 56,743
Loans and notes receivable from Safeguard distributors	[1]			55,861	66,872
Prepaid product discounts		$ 51,145	$ 58,237	45,994	51,145
Deferred sales commissions	[2]			9,530	9,682
Other				19,738	13,428
Other non-current assets				189,253	197,870
Amortization of deferred sales commissions		882	697
Prepaid product discounts [Roll Forward]
Balance, beginning of year		51,145	54,642
Additions	[3]	2,470	9,553
Amortization		(7,077)	(5,757)
Other		(544)	(201)
Balance, end of period		45,994	58,237
Prepaid product discount payments		7,321	9,189
Accrued liabilities
Deferred revenue	[4]			46,401	46,098
Employee cash bonuses				13,818	36,918
Operating lease liabilities				12,924	12,898
Prepaid product discounts due within one year				11,772	14,709
Customer rebates				7,857	8,944
Other				68,348	59,771
Accrued liabilities				161,120	179,338
Deferred revenue recognized		20,672
Loans and notes receivable from distributors [Member]
Loans and notes receivable from distributors [Line Items]
Loans and notes receivable, current				3,366	$ 3,511
Balance, beginning of year		284	284
Bad debt expense		5,382	0
Balance, end of period		10,415	$ 284
Loans and notes receivable form distributors by credit quality indicator
Write-offs		0
Recoveries		0
2019				6,313
2018				32,025
2017				22,690
2016				213
Prior				8,401
Total				69,642
Loans and notes receivable from distributors [Member] | One to two internal grade member [Member]
Loans and notes receivable form distributors by credit quality indicator
2019				6,313
2018				24,352
2017				22,690
2016				213
Prior				4,644
Total				58,212
Loans and notes receivable from distributors [Member] | Three to four internal grade [Member]
Loans and notes receivable form distributors by credit quality indicator
2019				0
2018				7,673
2017				0
2016				0
Prior				3,757
Total				$ 11,430
Loans and notes receivable from distributors [Member] | Accounting Standards Update No. 2016-13 [Member]
Loans and notes receivable from distributors [Line Items]
Adoption of ASU No. 2016-13 (Note 2)		4,749
Loan specific [Member]
Loans and notes receivable from distributors [Line Items]
Balance, end of period		$ 6,128

[1] Amount Includes the non-current portion of loans and note receivablles. The current portion of these receivables is included in other current assets on the consolidated balance sheets and was $3,366 as of March 31, 2020 and $3,511 as of December 31, 2019.

[2] Amortization of deferred sales commissions was $882 for the quarter ended March 31, 2020 and $697 for the quarter ended March 31, 2019.

[3] Prepaid product discounts are generally accrued upon contract execution. Cash payments for prepaid product discounts were $7,321 for the quarter ended March 31, 2020 and $9,189 for the quarter ended March 31, 2019.

[4] $20,672 of the December 31, 2019 amount was recognized as revenue during the quarter ended March 31, 2020.