Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Cash Flows from Operating Activities:
Net income	$ 805.1	$ 765.2	$ 1,029.8
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion, and amortization of intangibles	525.6	517.7	456.8
Amortization of deferred financing costs	2.3	2.2	2.1
Share-based compensation expense	48.8	40.0	35.6
Deferred income tax (benefit) provision	(4.2)	5.2	86.0
Net loss on asset disposals	19.5	9.1	15.2
Pension and post-retirement benefits expense, net of contributions	(19.5)	(30.8)	(47.4)
Other, net	24.2	13.3	2.0
(Increase) decrease in assets -
Accounts receivable	(110.7)	(1.4)	39.3
Inventories	(111.8)	(35.8)	(75.2)
Prepaid expenses and other current assets	(104.7)	(4.2)	(11.0)
Increase (decrease) in liabilities —
Accounts payable	18.3	11.4	(18.1)
Accrued liabilities	104.2	(8.2)	8.3
Federal and state income tax payable / receivable	(5.9)	31.4	(28.4)
Net cash provided by operating activities	1,191.2	1,315.1	1,495.0
Cash Flows from Investing Activities:
Additions to property, plant, and equipment	(669.7)	(469.7)	(824.2)
Additions to other long-term assets	(1.9)	(2.6)	(6.2)
Proceeds from asset disposals	1.3	1.6	2.2
Purchases of held-to-maturity debt securities	0.0	(400.0)	0.0
Proceeds from maturities of held-to-maturity debt securities	400.0	0.0	0.0
Purchases of available-for-sale debt securities	(114.3)	(107.2)	(126.1)
Proceeds from sales of available-for-sale debt securities	8.6	5.5	31.1
Proceeds from maturities of available-for-sale debt securities	98.2	97.3	87.6
Other, net	0.0	0.0	1.9
Net cash provided by (used for) investing activities	(277.8)	(875.1)	(833.7)
Cash Flows from Financing Activities:
Repayments of debt and finance lease obligations	(401.9)	(1.9)	(1.7)
Net proceeds received from issuance of debt	0.0	397.1	0.0
Financing costs paid	0.0	(1.1)	0.0
Common stock dividends paid	(448.8)	(448.9)	(420.3)
Repurchases of common stock	0.0	(41.5)	(522.6)
Shares withheld to cover employee restricted stock taxes	(25.7)	(15.7)	(15.4)
Net cash used for financing activities	(876.4)	(112.0)	(960.0)
Net increase (decrease) in cash and cash equivalents	37.0	328.0	(298.7)
Cash and cash equivalents, beginning of year	648.0	320.0	618.7
Cash and cash equivalents, end of year	$ 685.0	$ 648.0	$ 320.0