Leases (Schedule of Lease Cost) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Lessee, Lease, Description [Line Items]
Finance Lease, Right-of-Use Asset, Amortization	$ 410	$ 784
Finance Lease, Interest Expense	131	276
Operating Lease, Cost	8,700	22,780
Short-term Lease, Cost	245	463
Variable Lease, Cost	50	152
Lease, Cost	9,536	24,455
Drilling Rigs [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Cost	$ 6,100	$ 17,600