Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Cash Flows from Operating Activities:
Net income	$ 146.9	$ 190.1
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion, and amortization of intangibles	128.4	129.5
Amortization of deferred financing costs	0.6	0.5
Share-based compensation expense	19.4	15.3
Deferred income tax provision	8.4	2.7
Net loss on asset disposals	5.2	1.8
Pension and post-retirement benefits expense, net of contributions	1.5	5.0
Other, net	8.2	6.8
(Increase) decrease in assets -
Accounts receivable	(11.9)	0.4
Inventories	9.5	(26.1)
Prepaid expenses and other current assets	(149.4)	(29.3)
Increase (decrease) in liabilities -
Accounts payable	1.5	(5.0)
Accrued liabilities	70.3	(65.0)
Federal and state income taxes payable/receivable	21.8	53.7
Net cash provided by operating activities	260.4	280.4
Cash Flows from Investing Activities:
Additions to property, plant, and equipment	(76.7)	(112.4)
Additions to other long term assets	(1.4)	(1.6)
Proceeds from asset disposals	0.1	0.3
Purchases of available-for-sale debt securities	(32.8)	(29.6)
Proceeds from sales of available-for-sale debt securities	1.5	0.0
Proceeds from maturities of available-for-sale debt securities	28.3	27.9
Net cash used for investing activities	(81.0)	(115.4)
Cash Flows from Financing Activities:
Repayments of debt and finance lease obligations	(0.5)	(0.5)
Common stock dividends paid	(112.0)	(112.1)
Shares withheld to cover employee restricted stock taxes	(22.5)	(4.7)
Net cash used for financing activities	(135.0)	(117.3)
Net increase in cash and cash equivalents	44.4	47.7
Cash and cash equivalents, beginning of period	648.0	320.0
Cash and cash equivalents, end of period	$ 692.4	$ 367.7