Supplemental Financial Information (Interest Expense) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Supplemental Income Statement Elements [Abstract]
Interest on revolving credit facility	$ 0	$ 612	$ 106	$ 3,079
Interest rate swap settlements	0	2,769	0	3,191
Line of credit fees	292	112	856	430
Debt issuance amortization costs	178	138	536	414
Interest on finance leases	11	35	270	100
Interest income	(64)	(135)	(409)	(724)
Other	24	22	93	49
Total interest expense, net	$ 441	$ 3,553	$ 1,452	$ 6,539

Amount of amortization expense attributable to debt issuance costs.

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Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

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Amount of interest expense on finance lease liability.

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Aggregate amount of interest paid or due on all long-term debt.

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Amount of the fee for available but unused credit capacity under the credit facility.

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