Consolidated Statements of Income - USD ($) shares in Thousands, $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Operating Revenues
Total operating revenues		$ 2,839.0	$ 3,657.6	$ 8,403.4	$ 10,574.4
Operating Expenses
Depreciation and amortization		40.6	37.6	119.5	113.8
Selling, general and administrative		53.7	36.0	130.0	105.7
Accretion of asset retirement obligations		0.6	0.6	1.7	1.6
Total operating expenses		2,738.7	3,537.1	7,938.2	10,379.6
Net settlement proceeds		0.0	0.0	0.0	0.1
Gain (loss) on sale of assets		0.0	0.2	1.4	0.1
Income (loss) from operations		100.3	120.7	466.6	195.0
Other income (expense)
Interest income		0.0	0.8	1.0	2.4
Interest expense		(12.4)	(15.3)	(38.7)	(42.1)
Loss on early debt extinguishment		0.0	(14.8)	0.0	(14.8)
Other nonoperating income (expense)		0.2	(0.1)	(0.5)	0.0
Total other income (expense)		(12.2)	(29.4)	(38.2)	(54.5)
Income (loss) before income taxes		88.1	91.3	428.4	140.5
Income tax expense (benefit)		21.2	22.1	103.3	33.3
Net Income		$ 66.9	$ 69.2	$ 325.1	$ 107.2
Basic and Diluted Earnings Per Common Share
Basic (in dollars per share)		$ 2.30	$ 2.20	$ 11.00	$ 3.35
Diluted (in dollars per share)		$ 2.27	$ 2.18	$ 10.88	$ 3.33
Weighted-Average Common Shares Outstanding (in thousands):
Basic (in shares)		29,111	31,447	29,546	31,961
Diluted (in shares)		29,499	31,704	29,887	32,189
Supplemental information:
Excise taxes		$ 447.0	$ 498.9	$ 1,300.7	$ 1,452.5
Product
Operating Revenues
Total operating revenues	[1]	2,056.0	2,965.5	6,125.1	8,595.0
Operating Expenses
Operating expenses	[1]	1,862.2	2,749.6	5,409.8	8,104.8
Merchandise sales
Operating Revenues
Total operating revenues		756.8	681.1	2,211.4	1,946.1
Operating Expenses
Operating expenses		638.7	569.9	1,867.4	1,631.9
Other operating revenues
Operating Revenues
Total operating revenues		26.2	11.0	66.9	33.3
Operating Expenses
Operating expenses		$ 142.9	$ 143.4	$ 409.8	$ 421.8

[1] Includes excise taxes of $447.0 million for the three months ended September 30, 2020, $498.9 million for the three months ended September 30, 2019, $1,300.7 million for the nine months ended September 30, 2020 and $1,452.5 million the nine months ended September 30, 2019.