Financial Instruments and Risk Management (Carrying Value of Assets and Liabilities Recorded at Fair Value on Recurring Basis) (Details) - Fair Value - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Assets:
Assets	$ 0	$ 4,280
Liabilities:
Liabilities	724,364	472,528
Nonqualified employee savings plan
Liabilities:
Nonqualified employee savings plan	17,038	16,962
Commodity collars
Assets:
Derivative assets	0	4,280
Liabilities:
Derivative liability	162,123	19,533
Contingent consideration
Liabilities:
Contingent consideration	239,108	196,151
Commodity swaps
Liabilities:
Derivative liability	306,095	239,882
Level 1
Assets:
Assets	0	0
Liabilities:
Liabilities	17,038	16,962
Level 1 | Nonqualified employee savings plan
Liabilities:
Nonqualified employee savings plan	17,038	16,962
Level 1 | Commodity collars
Assets:
Derivative assets	0	0
Liabilities:
Derivative liability	0	0
Level 1 | Contingent consideration
Liabilities:
Contingent consideration	0	0
Level 1 | Commodity swaps
Liabilities:
Derivative liability	0	0
Level 2
Assets:
Assets	0	4,280
Liabilities:
Liabilities	468,218	259,415
Level 2 | Nonqualified employee savings plan
Liabilities:
Nonqualified employee savings plan	0	0
Level 2 | Commodity collars
Assets:
Derivative assets	0	4,280
Liabilities:
Derivative liability	162,123	19,533
Level 2 | Contingent consideration
Liabilities:
Contingent consideration	0	0
Level 2 | Commodity swaps
Liabilities:
Derivative liability	306,095	239,882
Level 3
Assets:
Assets	0	0
Liabilities:
Liabilities	239,108	196,151
Level 3 | Nonqualified employee savings plan
Liabilities:
Nonqualified employee savings plan	0	0
Level 3 | Commodity collars
Assets:
Derivative assets	0	0
Liabilities:
Derivative liability	0	0
Level 3 | Contingent consideration
Liabilities:
Contingent consideration	239,108	196,151
Level 3 | Commodity swaps
Liabilities:
Derivative liability	$ 0	$ 0