Supplemental Oil and Gas Information (Unaudited) - Results of Operations for Oil and Gas Producing Activities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Revenues
Revenues	$ 2,801,200	$ 1,751,700	$ 2,817,100
Other operating revenues	17,500	7,700	8,500
Total revenues	2,818,700	1,759,400	2,825,600
Costs and expenses
Lease operating expenses	539,500	600,100	605,200
Severance and ad valorem taxes	41,200	28,500	48,000
Transportation, gathering and processing	187,028	172,399	176,315
Restructuring expenses	0	49,994	0
Exploration costs charged to expense	50,100	59,700	67,300
Undeveloped lease amortization	18,900	26,800	28,000
Depreciation, depletion and amortization	782,100	964,900	1,125,200
Accretion of asset retirement obligations	46,600	42,200	40,500
Impairment of assets	196,296	1,206,284	0
Selling and general expenses	43,600	48,800	126,800
Other expenses (benefits)	31,000	21,000	47,400
Total costs and expenses	1,929,300	3,157,800	2,264,700
Results of operations before taxes	889,400	(1,398,400)	560,900
Income tax expense (benefit)	172,700	(263,500)	100,300
Results of operations	716,700	(1,134,900)	460,600
Net natural gas revenue
Costs and expenses
Restructuring expenses		1,200
Impairment of assets	189,300	1,192,200
Crude Oil and Natural Gas Liquids
Revenues
Revenues	2,433,500	1,511,600	2,584,800
Natural Gas
Revenues
Revenues	367,700	240,100	232,300
U.S.
Revenues
Revenues	2,321,500	1,405,300	2,359,700
Other operating revenues	16,000	6,500	7,300
Total revenues	2,337,500	1,411,800	2,367,000
Costs and expenses
Lease operating expenses	406,400	476,900	461,500
Severance and ad valorem taxes	39,600	27,200	46,600
Transportation, gathering and processing	126,500	127,700	140,800
Exploration costs charged to expense	30,400	35,500	21,400
Undeveloped lease amortization	11,100	17,200	23,100
Depreciation, depletion and amortization	616,500	749,400	878,700
Accretion of asset retirement obligations	36,900	36,600	34,400
Selling and general expenses	20,500	24,600	74,300
Other expenses (benefits)	99,400	21,500	52,200
Total costs and expenses	1,387,300	2,670,300	1,733,000
Results of operations before taxes	950,200	(1,258,500)	634,000
Income tax expense (benefit)	183,900	(244,200)	115,600
Results of operations	766,300	(1,014,300)	518,400
U.S. | Net natural gas revenue
Costs and expenses
Restructuring expenses		1,200
Impairment of assets	0	1,152,500
U.S. | Crude Oil and Natural Gas Liquids
Revenues
Revenues	2,199,700	1,335,800	2,285,800
U.S. | Natural Gas
Revenues
Revenues	121,800	69,400	73,900
Canada | Net natural gas revenue
Costs and expenses
Restructuring expenses		0
Canada | Conventional gas
Revenues
Revenues	474,800	344,600	445,800
Other operating revenues	1,500	1,200	1,200
Total revenues	476,300	345,800	447,000
Costs and expenses
Lease operating expenses	136,300	121,600	142,400
Severance and ad valorem taxes	1,600	1,300	1,400
Transportation, gathering and processing	60,500	44,700	35,500
Exploration costs charged to expense	400	600	600
Undeveloped lease amortization	200	400	1,300
Depreciation, depletion and amortization	163,800	213,200	243,000
Accretion of asset retirement obligations	9,700	5,600	6,100
Selling and general expenses	16,500	17,100	30,000
Other expenses (benefits)	(66,200)	(2,300)	(6,100)
Total costs and expenses	494,100	402,200	454,200
Results of operations before taxes	(17,800)	(56,400)	(7,200)
Income tax expense (benefit)	(1,700)	(21,400)	(2,900)
Results of operations	(16,100)	(35,000)	(4,300)
Canada | Conventional gas | Net natural gas revenue
Costs and expenses
Impairment of assets	171,300	0
Canada | Crude Oil and Natural Gas Liquids | Conventional gas
Revenues
Revenues	228,900	174,000	287,400
Canada | Natural Gas | Conventional gas
Revenues
Revenues	245,900	170,600	158,400
Other
Revenues
Revenues	4,900	1,800	11,600
Other operating revenues	0	0	0
Total revenues	4,900	1,800	11,600
Costs and expenses
Lease operating expenses	(3,200)	1,600	1,300
Severance and ad valorem taxes	0	0	0
Transportation, gathering and processing	0	0	0
Exploration costs charged to expense	19,300	23,600	45,300
Undeveloped lease amortization	7,600	9,200	3,600
Depreciation, depletion and amortization	1,800	2,300	3,500
Accretion of asset retirement obligations	0	0	0
Selling and general expenses	6,600	7,100	22,500
Other expenses (benefits)	(2,200)	1,800	1,300
Total costs and expenses	47,900	85,300	77,500
Results of operations before taxes	(43,000)	(83,500)	(65,900)
Income tax expense (benefit)	(9,500)	2,100	(12,400)
Results of operations	(33,500)	(85,600)	(53,500)
Other | Net natural gas revenue
Costs and expenses
Restructuring expenses		0
Impairment of assets	18,000	39,700
Other | Crude Oil and Natural Gas Liquids
Revenues
Revenues	4,900	1,800	11,600
Other | Natural Gas
Revenues
Revenues	$ 0	$ 0	$ 0