CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 449,023	$ 452,575
Short-term marketable securities	65,034	81,724
Accounts receivable, net of allowances aggregating $48,826 and $40,140, respectively	1,026,226	792,734
Unbilled accounts receivable	134,742	94,963
Inventories and supplies	294,220	250,692
Prepaid expenses and other current assets	71,846	68,483
Total current assets	2,041,091	1,741,171
Property, plant and equipment, net	1,923,675	1,863,175
Other assets:
Operating lease right-of-use assets	161,668	161,797
Goodwill	1,246,327	1,227,042
Permits and other intangibles, net	621,834	644,912
Other	78,032	15,602
Total other assets	2,107,861	2,049,353
Total assets	6,072,627	5,653,699
Current liabilities:
Current portion of long-term debt	17,535	17,535
Accounts payable	416,913	359,866
Deferred revenue	93,425	83,749
Accrued expenses and other current liabilities	405,257	391,414
Current portion of closure, post-closure and remedial liabilities	36,904	25,136
Current portion of operating lease liabilities	47,879	47,614
Total current liabilities	1,017,913	925,314
Other liabilities:
Closure and post-closure liabilities, less current portion of $17,373 and $12,015, respectively	89,399	87,088
Remedial liabilities, less current portion of $19,531 and $13,121, respectively	97,737	98,752
Long-term debt, less current portion	2,507,946	2,517,024
Operating lease liabilities, less current portion	116,607	117,991
Deferred tax liabilities	326,842	314,853
Other long-term liabilities	78,602	78,790
Total other liabilities	3,217,133	3,214,498
Commitments and contingent liabilities (See Note 17)
Stockholders’ equity:
Common stock	541	544
Additional paid-in capital	506,359	536,377
Accumulated other comprehensive loss	(171,567)	(196,012)
Accumulated earnings	1,502,248	1,172,978
Total stockholders’ equity	1,837,581	1,513,887
Total liabilities and stockholders’ equity	$ 6,072,627	$ 5,653,699