CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 492,603	$ 452,575
Short-term marketable securities	62,033	81,724
Accounts receivable, net of allowances aggregating $45,253 and $40,140, respectively	964,603	792,734
Unbilled accounts receivable	107,010	94,963
Inventories and supplies	324,994	250,692
Prepaid expenses and other current assets	82,518	68,483
Total current assets	2,033,761	1,741,171
Property, plant and equipment, net	1,980,302	1,863,175
Other assets:
Operating lease right-of-use assets	166,181	161,797
Goodwill	1,246,878	1,227,042
Permits and other intangibles, net	620,782	644,912
Other	81,803	15,602
Total other assets	2,115,644	2,049,353
Total assets	6,129,707	5,653,699
Current liabilities:
Current portion of long-term debt	10,000	17,535
Accounts payable	446,629	359,866
Deferred revenue	94,094	83,749
Accrued expenses and other current liabilities	396,716	391,414
Current portion of closure, post-closure and remedial liabilities	23,123	25,136
Current portion of operating lease liabilities	49,532	47,614
Total current liabilities	1,020,094	925,314
Other liabilities:
Closure and post-closure liabilities, less current portion of $13,205 and $12,015, respectively	105,596	87,088
Remedial liabilities, less current portion of $9,918 and $13,121, respectively	106,372	98,752
Long-term debt, less current portion	2,414,828	2,517,024
Operating lease liabilities, less current portion	119,259	117,991
Deferred tax liabilities	350,389	314,853
Other long-term liabilities	90,847	78,790
Total other liabilities	3,187,291	3,214,498
Commitments and contingent liabilities (See Note 18)
Stockholders' equity:
Common stock	541	544
Additional paid-in capital	504,240	536,377
Accumulated other comprehensive loss	(167,181)	(196,012)
Accumulated earnings	1,584,722	1,172,978
Total stockholders' equity	1,922,322	1,513,887
Total liabilities and stockholders' equity	$ 6,129,707	$ 5,653,699