Consolidated Statements of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Cash Flows from Operating Activities:
Net income	$ 584.0	$ 576.0
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion, and amortization of intangibles	389.6	386.8
Amortization of deferred financing costs	1.8	1.6
Share-based compensation expense	39.6	32.5
Deferred income tax benefit	(18.0)	(7.7)
Net loss on asset disposals	12.9	5.2
Pension and post-retirement benefits expense, net of contributions	(20.8)	(35.8)
Other, net	23.7	11.0
Increase in assets -
Accounts receivable	(182.8)	(13.4)
Inventories	(48.8)	(8.8)
Prepaid expenses and other current assets	(129.7)	(6.8)
Increase (decrease) in liabilities -
Accounts payable	36.1	(1.1)
Accrued liabilities	158.8	(3.8)
Federal and state income taxes payable/receivable	19.4	44.1
Net cash provided by operating activities	865.8	979.8
Cash Flows from Investing Activities:
Additions to property, plant, and equipment	(468.4)	(328.6)
Additions to other long-term assets	(1.9)	(2.5)
Proceeds from asset disposals	0.8	1.5
Purchases of available-for-sale debt securities	(91.9)	(76.1)
Proceeds from sales of available-for-sale debt securities	3.8	2.2
Proceeds from maturities of available-for-sale debt securities	83.1	72.4
Proceeds from maturities of held-to-maturity debt securities	400.0	0.0
Net cash used for investing activities	(74.5)	(331.1)
Cash Flows from Financing Activities:
Repayments of debt and finance lease obligations	(401.4)	(1.4)
Common stock dividends paid	(336.5)	(336.9)
Repurchases of common stock	0.0	(41.5)
Shares withheld to cover employee restricted stock taxes	(24.8)	(15.7)
Net cash used for financing activities	(762.7)	(395.5)
Net increase in cash and cash equivalents	28.6	253.2
Cash and cash equivalents, beginning of period	648.0	320.0
Cash and cash equivalents, end of period	$ 676.6	$ 573.2