Leases (Breakdown of Lease Expense) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Leases
Operating lease cost	$ 4,600	$ 4,501
Amortization of leased assets	2,588	2,114
Interest on lease liabilities	221	233
Short-term lease cost	2,661	2,880
Sublease income	(15)	(148)
Lease expense	$ 10,055	$ 9,580

Amount of interest expense on finance lease liability.

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- Definition

Amount of amortization expense attributable to right-of-use asset from finance lease.

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- Definition

Amount of lease cost recognized by lessee for lease contract.

+ References

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- Definition

Amount of single lease cost, calculated by allocation of remaining cost of lease over remaining lease term. Includes, but is not limited to, single lease cost, after impairment of right-of-use asset, calculated by amortization of remaining right-of-use asset and accretion of lease liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
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Amount of short-term lease cost, excluding expense for lease with term of one month or less.

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- Definition

Amount of sublease income excluding finance and operating lease expense.

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