CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 337,825	$ 444,698
Short-term marketable securities	104,811	106,101
Accounts receivable, net of allowances aggregating $47,129 and $42,209, respectively	1,039,763	983,111
Unbilled accounts receivable	165,592	107,859
Inventories and supplies	354,310	327,511
Prepaid expenses and other current assets	103,495	82,939
Total current assets	2,105,796	2,052,219
Property, plant and equipment, net	2,330,484	2,193,318
Other assets:
Operating lease right-of-use assets	206,577	187,060
Goodwill	1,487,821	1,287,736
Permits and other intangibles, net	739,975	602,797
Other long-term assets	69,170	59,739
Total other assets	2,503,543	2,137,332
Total assets	6,939,823	6,382,869
Current liabilities:
Current portion of long-term debt	15,102	10,000
Accounts payable	452,848	451,806
Deferred revenue	106,425	95,230
Accrued expenses and other current liabilities	349,435	397,157
Current portion of closure, post-closure and remedial liabilities	29,179	26,914
Current portion of operating lease liabilities	64,534	56,430
Total current liabilities	1,017,523	1,037,537
Other liabilities:
Closure and post-closure liabilities, less current portion of $14,079 and $13,556, respectively	105,493	105,044
Remedial liabilities, less current portion of $15,100 and $13,358, respectively	94,686	97,885
Long-term debt, less current portion	2,778,624	2,291,717
Operating lease liabilities, less current portion	145,544	131,743
Deferred tax liabilities	361,223	353,107
Other long-term liabilities	125,393	118,330
Total other liabilities	3,610,963	3,097,826
Commitments and contingent liabilities (See Note 15)
Stockholders’ equity:
Common stock	539	539
Additional paid-in capital	458,014	459,728
Accumulated other comprehensive loss	(179,626)	(175,339)
Retained earnings	2,032,410	1,962,578
Total stockholders’ equity	2,311,337	2,247,506
Total liabilities and stockholders’ equity	$ 6,939,823	$ 6,382,869