Other Assets (Schedule of Other Assets) (Details) - USD ($) $ in Thousands	May 14, 2021	Dec. 31, 2021	Dec. 31, 2020
Other Assets [Abstract]
Prepayments		$ 24,226	$ 24,112
Long service leave receivable		9,136	10,990
Tax credits receivable		4,440	0
Other		9,845	8,904
Total other current assets		47,647	44,006
Favorable mineral leases		3,645	3,925
Deferred debt issue costs		4,310	7,475
Long service leave receivable		550	864
Tax credits receivable		11,223	0
Total other non-current assets		19,728	$ 12,264
Receivable related to employment enhancement tax credit		$ 15,700
Employment enhancement tax credit excess rate		85.00%
Write off of Deferred Debt Issuance Cost	$ 5,700