UNAUDITED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Cash flows from operating activities:
Net income	$ 318,325	$ 279,507
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	295,632	267,425
Allowance for doubtful accounts	5,674	2,620
Amortization of deferred financing costs and debt discount	4,623	4,036
Accretion of environmental liabilities	10,139	10,281
Changes in environmental liability estimates	4,347	3,258
Deferred income taxes	(418)	(356)
Other expense, net	2,431	833
Stock-based compensation	20,690	14,809
Loss on early extinguishment of debt	0	2,362
Environmental expenditures	(19,679)	(24,064)
Changes in assets and liabilities, net of acquisitions:
Accounts receivable and unbilled accounts receivable	(145,647)	(46,445)
Inventories and supplies	(39,673)	12,691
Other current and long-term assets	(47,826)	(18,190)
Accounts payable	30,004	(40,013)
Other current and long-term liabilities	35,211	(13,062)
Net cash from operating activities	473,833	455,692
Cash flows used in investing activities:
Additions to property, plant and equipment	(369,826)	(311,906)
Proceeds from sale and disposal of fixed assets	6,353	5,129
Acquisitions, net of cash acquired	(474,011)	(119,596)
Proceeds from sale of business	750	750
Additions to intangible assets including costs to obtain or renew permits	(2,545)	(1,507)
Purchases of available-for-sale securities	(73,682)	(104,329)
Proceeds from sale of available-for-sale securities	100,021	84,390
Net cash used in investing activities	(812,940)	(447,069)
Cash flows from (used in) financing activities:
Change in uncashed checks	(5,852)	3,004
Tax payments related to withholdings on vested restricted stock	(11,514)	(10,886)
Repurchases of common stock	(30,215)	(18,000)
Deferred financing costs paid	(8,316)	(6,371)
Payments on finance leases	(23,596)	(11,594)
Principal payments on debt	(11,327)	(621,475)
Proceeds from issuance of debt, net of discount	499,375	500,000
Borrowing from revolving credit facility	0	114,000
Payment on revolving credit facility	0	(114,000)
Net cash from (used in) financing activities	408,555	(165,322)
Effect of exchange rate change on cash	(1,775)	61
Increase (decrease) in cash and cash equivalents	67,673	(156,638)
Cash and cash equivalents, beginning of period	444,698	492,603
Cash and cash equivalents, end of period	512,371	335,965
Cash payments for interest and income taxes:
Interest paid	134,177	100,813
Income taxes paid, net of refunds	100,752	107,328
Non-cash investing activities:
Property, plant and equipment accrued	43,604	29,127
ROU assets obtained in exchange for operating lease liabilities	98,927	61,741
ROU assets obtained in exchange for finance lease liabilities	$ 53,391	$ 26,317