Leases (Components Of Lease Expense) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Lessee, Lease, Description [Line Items]
Operating lease expense	$ 3,563	$ 4,047	$ 10,991	$ 11,749
Short-term lease expense	24,502	17,786	64,823	50,843
Lease expense, gross	28,065	21,833	75,814	62,592
Less: Sublease income	193	263	851	784
Total lease expense	$ 27,872	$ 21,570	$ 74,963	$ 61,808
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