Consolidated Balance Sheets - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Current assets
Cash and cash equivalents	$ 124.8	$ 60.5
Marketable securities, current	8.5	17.9
Accounts receivable—trade, less allowance for doubtful accounts of $1.5 and $0.3 at 2023 and 2022, respectively	344.2	281.7
Inventories, at lower of cost or market	335.4	319.1
Prepaid expenses and other current assets	27.4	47.6
Total current assets	840.3	726.8
Marketable securities, non-current	7.4	4.4
Property, plant and equipment, at cost less accumulated depreciation and amortization of $1,694.2 and $1,553.1 at 2023 and 2022, respectively	2,520.1	2,459.3
Operating lease right of use assets, net	451.9	449.6
Intangible assets, net of amortization	139.9	140.4
Goodwill	328.0	328.0
Other assets	17.7	14.7
Total assets	4,305.3	4,123.2
Current liabilities
Current maturities of long-term debt	15.0	15.0
Trade accounts payable and accrued liabilities	800.6	839.2
Income taxes payable	11.6	0.0
Total current liabilities	827.2	854.2
Long-term debt, including capitalized lease obligations	1,786.4	1,791.9
Deferred income taxes	327.7	327.4
Asset retirement obligations	44.0	43.3
Non-current operating lease liabilities	449.8	444.2
Deferred credits and other liabilities	26.1	21.5
Total liabilities	3,461.2	3,482.5
Stockholders' Equity
Preferred Stock, par $0.01 (authorized 20,000,000 shares, none outstanding)	0.0	0.0
Common Stock, par $0.01 (authorized 200,000,000 shares, 46,767,164 shares issued at 2023 and 2022, respectively)	0.5	0.5
Treasury stock (25,490,133 and 25,017,324 shares held at 2023 and 2022, respectively)	(2,795.9)	(2,633.3)
Additional paid in capital (APIC)	502.7	518.9
Retained earnings	3,136.8	2,755.1
Accumulated other comprehensive income (loss) (AOCI)	0.0	(0.5)
Total stockholders' equity	844.1	640.7
Total liabilities and stockholders' equity	$ 4,305.3	$ 4,123.2

Sum of the carrying values as of the balance sheet date of obligations incurred through that date and due within one year (or the operating cycle, if longer), including liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received, taxes, interest, rent and utilities, accrued salaries and bonuses, payroll taxes and fringe benefits.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19,20)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1