Leases (Components Of Lease Expense) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Lessee, Lease, Description [Line Items]
Operating lease expense	$ 3,660	$ 3,563	$ 11,085	$ 10,991
Short-term lease expense	17,951	24,502	57,377	64,823
Lease expense, gross	21,611	28,065	68,462	75,814
Less: Sublease income	176	193	522	851
Total lease expense	$ 21,435	$ 27,872	$ 67,940	$ 74,963
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