Supplemental balance sheet and cash flow information (other non-current assets) (Details) - USD ($) $ in Thousands		3 Months Ended		12 Months Ended
		Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2019	Dec. 31, 2020
Other non-current assets
Postretirement benefit plan asset		$ 72,775			$ 71,208
Prepaid product discounts		51,044	$ 45,994	$ 51,145	50,602
Cloud computing arragements		38,249			29,242
Loans and notes receivable from distributors, net of allowances for doubtful accounts	[1]	27,182			35,068
Deferred sales commissions	[2]	15,461			9,199
Other		13,124			13,360
Other non-current assets		217,835			208,679
Loans and notes receivable, current		1,704			$ 2,008
Amortization of deferred sales commissions		972	882
Loans and notes receivable from distributors, allowances for uncollectible accounts [Line Items]
Accounting Standards Update [Extensible List]				us-gaap:AccountingStandardsUpdate201613Member
Loans and notes receivable from distributors [Member]
Loans and notes receivable from distributors, allowances for uncollectible accounts [Line Items]
Balance, beginning of year		3,995	284
Bad debt (benefit) expense		(634)	5,382
Balance, end of period		3,361	10,415	$ 284
Write-offs		0
Recoveries		0
Loans and notes receivable from distributors, credit quality information
2020		1,310
2019		3,166
2018		14,546
2017		11,744
Prior		1,481
Total		32,247
Loans and notes receivable from distributors [Member] | 1-2 internal grade member [Member]
Loans and notes receivable from distributors, credit quality information
2020		1,310
2019		587
2018		14,546
2017		11,744
Prior		1,481
Total		29,668
Loans and notes receivable from distributors [Member] | 3-4 internal grade [Member]
Loans and notes receivable from distributors, credit quality information
2020		0
2019		2,579
2018		0
2017		0
Prior		0
Total		$ 2,579
Loans and notes receivable from distributors [Member] | Adoption of Accounting Standards Update [Member]
Loans and notes receivable from distributors, allowances for uncollectible accounts [Line Items]
Balance, beginning of year			$ 4,749
Balance, end of period				$ 4,749

[1] Amount Includes the non-current portion of loans and notes receivable. The current portion of these receivables is included in other current assets on the consolidated balance sheets and was $1,704 as of March 31, 2021 and $2,008 as of December 31, 2020.

[2] Amortization of deferred sales commissions was $972 for the quarter ended March 31, 2021 and $882 for the quarter ended March 31, 2020.