Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash Flows from Operating Activities:
Net income	$ 765.2	$ 1,029.8	$ 841.1
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion, and amortization of intangibles	517.7	456.8	417.5
Amortization of deferred financing costs	2.2	2.1	4.4
Loss on early extinguishment of debt	0.0	0.0	56.1
Share-based compensation expense	40.0	35.6	35.5
Deferred income tax provision	5.2	86.0	59.4
Net loss on asset disposals	9.1	15.2	6.1
Pension and post-retirement benefits expense, net of contributions	(30.8)	(47.4)	(50.5)
Other, net	13.3	2.0	11.9
(Increase) decrease in assets -
Accounts receivable	(1.4)	39.3	(227.2)
Inventories	(35.8)	(75.2)	(105.5)
Prepaid expenses and other current assets	(4.2)	(11.0)	(2.7)
Increase (decrease) in liabilities —
Accounts payable	11.4	(18.1)	12.2
Accrued liabilities	(8.2)	8.3	37.9
Federal and state income tax payable / receivable	31.4	(28.4)	(2.1)
Net cash provided by operating activities	1,315.1	1,495.0	1,094.1
Cash Flows from Investing Activities:
Additions to property, plant, and equipment	(469.7)	(824.2)	(605.1)
Acquisitions of businesses, net of cash acquired	0.0	0.0	(194.9)
Additions to other long-term assets	(2.6)	(6.2)	(1.8)
Proceeds from asset disposals	1.6	2.2	7.9
Purchases of held-to-maturity debt securities	(400.0)	0.0	0.0
Purchases of marketable debt securities	(107.2)	(126.1)	(127.4)
Proceeds from sales of available-for-sale debt securities	5.5	31.1	26.7
Proceeds from maturities of available-for-sale debt securities	97.3	87.6	100.2
Other, net	0.0	1.9	0.0
Net cash used for investing activities	(875.1)	(833.7)	(794.4)
Cash Flows from Financing Activities:
Repayments of debt and finance lease obligations	(1.9)	(1.7)	(757.7)
Net proceeds received from issuance of debt	397.1	0.0	690.2
Financing costs paid	(1.1)	0.0	(2.4)
Common stock dividends paid	(448.9)	(420.3)	(379.8)
Repurchases of common stock	(41.5)	(522.6)	(193.0)
Shares withheld to cover employee restricted stock taxes	(15.7)	(15.4)	(12.9)
Net cash used for financing activities	(112.0)	(960.0)	(655.6)
Net increase (decrease) in cash and cash equivalents	328.0	(298.7)	(355.9)
Cash and cash equivalents, beginning of year	320.0	618.7	974.6
Cash and cash equivalents, end of year	$ 648.0	$ 320.0	$ 618.7