Leases (Components Of Lease Expense) (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Lessee, Lease, Description [Line Items]
Operating lease expense		$ 3,661	$ 3,921	$ 7,428	$ 7,702
Short-term lease expense	[1]	23,056	16,486	40,321	33,057
Lease expense, gross		26,717	20,407	47,749	40,759
Less: Sublease income		329	262	658	521
Total lease expense		$ 26,388	$ 20,145	$ 47,091	$ 40,238
Minimum [Member]
Lessee, Lease, Description [Line Items]
Short term lease, lease term				1 month
Maximum [Member]
Lessee, Lease, Description [Line Items]
Short term lease, lease term				1 year

[1] Short-term lease expense includes all leases with lease terms ranging from less than one month to one year. Short-term leases include, among other things, construction equipment rented on an as-needed basis as well as temporary housing.