Fair Value Measurements (Assets and Liabilities Measured on Recurring Basis) (Details) - Recurring - USD ($) $ in Thousands		Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020
Assets and liabilities measured at fair value on a recurring basis
Commodity derivatives, net	[1]	$ 335,095	$ 177,467	$ 63,516
Provisionally price contracts	[2]	3,335	(29,025)	(27,731)
Convertible preferred securities	[3]	11,066	8,849	8,654
Other assets and liabilities	[4]	(7,694)	(18,086)	(27,212)
Total		341,802	139,205	17,227
Level 1
Assets and liabilities measured at fair value on a recurring basis
Commodity derivatives, net	[1]	122,877	51,369	11,951
Provisionally price contracts	[2]	28,469	19,793	(5,190)
Convertible preferred securities	[3]	0	0	0
Other assets and liabilities	[4]	4,171	7,972	4,998
Total		155,517	79,134	11,759
Level 2
Assets and liabilities measured at fair value on a recurring basis
Commodity derivatives, net	[1]	212,218	126,098	51,565
Provisionally price contracts	[2]	(25,134)	(48,818)	(22,541)
Convertible preferred securities	[3]	0	0	0
Other assets and liabilities	[4]	(11,865)	(26,058)	(32,210)
Total		175,219	51,222	(3,186)
Level 3
Assets and liabilities measured at fair value on a recurring basis
Commodity derivatives, net	[1]	0	0	0
Provisionally price contracts	[2]	0	0	0
Convertible preferred securities	[3]	11,066	8,849	8,654
Other assets and liabilities	[4]	0	0	0
Total		$ 11,066	$ 8,849	$ 8,654

[1] Includes associated cash posted/received as collateral

[2] Included in "Provisionally priced contracts" are those instruments based only on underlying futures values (Level 1) and delayed price contracts (Level 2)

[3] Recorded in “Other assets, net” on the Company’s Condensed Consolidated Balance Sheets related to certain available for sale securities.

[4] Included in other assets and liabilities are assets held by the Company to fund deferred compensation plans and foreign exchange derivative contracts (Level 1), as well as interest rate derivatives (Level 2).