Lease Commitments - Lease Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Lessee, Lease, Description [Line Items]
Total operating lease cost	$ 42,090	$ 41,953
Interest on finance lease liabilities	96	32
Total finance lease cost	926	384
Net lease cost	43,016	42,337
Short-term lease, cost	7,904	7,328
Variable lease, cost	2,385	3,480
Cost of sales
Lessee, Lease, Description [Line Items]
Total operating lease cost	35,305	36,321
Amortization of finance lease assets	698	352
Selling general & administrative expenses
Lessee, Lease, Description [Line Items]
Total operating lease cost	6,785	5,632
Amortization of finance lease assets	$ 132	$ 0