Leases (Lease Assets and Liabilities) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Finance lease cost:
Amortization of right-of-use assets	$ 114	$ 749	$ 231	$ 1,442
Interest on lease liabilities	26	117	53	230
Operating lease cost	389	308	779	616
Short-term lease cost	92	154	310	283
Variable lease cost	0	95	0	190
Sublease income	0	(1,198)	0	(2,396)
Total lease cost	621	225	1,373	365
Capitalized operating lease cost	0	3,371	0	6,706
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows for finance leases	(26)	(117)	(53)	(230)
Operating cash flows for operating leases	(344)	(308)	(689)	(616)
Investing cash flows for operating leases	0	(2,965)	0	(3,988)
Financing cash flows for finance leases	(107)	(746)	(212)	(1,445)
Right-of-use assets obtained in exchange for new finance lease liabilities	$ 0	$ 717	$ 0	$ 1,387
Operating lease cost, drilling rigs, minimum term			30 days