Leases (Components Of Lease Expense) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Lessee, Lease, Description [Line Items]
Operating lease expense	$ 3,707	$ 3,661	$ 7,425	$ 7,428
Short-term lease expense	18,301	23,056	39,426	40,321
Lease expense, gross	22,008	26,717	46,851	47,749
Less: Sublease income	176	329	346	658
Total lease expense	$ 21,832	$ 26,388	$ 46,505	$ 47,091
Minimum
Lessee, Lease, Description [Line Items]
Short term lease, lease term			1 month
Maximum
Lessee, Lease, Description [Line Items]
Short term lease, lease term			1 year