Consolidated Statements of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Cash Flows from Operating Activities:
Net income	$ 392.8	$ 555.7
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion, and amortization of intangibles	257.4	224.0
Amortization of deferred financing costs	1.1	1.0
Share-based compensation expense	24.8	21.6
Deferred income tax provision	(5.4)	28.8
Loss on asset disposals	3.2	12.1
Pension and post-retirement benefits expense, net of contributions	9.8	1.7
Other, net	12.7	0.2
(Increase) decrease in assets -
Accounts receivable	7.8	(140.9)
Inventories	(14.9)	(51.7)
Prepaid expenses and other current assets	(17.5)	(27.3)
Increase (decrease) in liabilities -
Accounts payable	(32.2)	25.1
Accrued liabilities	(43.0)	(18.3)
Federal and state income taxes receivable	43.7	12.3
Net cash provided by operating activities	640.3	644.3
Cash Flows from Investing Activities:
Additions to property, plant, and equipment	(238.8)	(397.5)
Additions to other long term assets	(2.2)	(2.6)
Proceeds from asset disposals	0.4	0.4
Purchases of marketable debt securities	(55.7)	(64.2)
Proceeds from sales of marketable debt securities	1.2	19.9
Proceeds from maturities of marketable debt securities	52.9	44.0
Other, net	0.0	1.9
Net cash used for investing activities	(242.2)	(398.1)
Cash Flows from Financing Activities:
Repayments of debt and finance lease obligations	(0.9)	(0.9)
Common stock dividends paid	(224.5)	(187.2)
Shares withheld to cover employee restricted stock taxes	(15.6)	(9.5)
Net cash used for financing activities	(241.0)	(197.6)
Net increase in cash and cash equivalents	157.1	48.6
Cash and cash equivalents, beginning of period	320.0	618.7
Cash and cash equivalents, end of period	$ 477.1	$ 667.3