CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 335,965	$ 492,603
Short-term marketable securities	84,007	62,033
Accounts receivable, net of allowances aggregating $42,342 and $45,253, respectively	1,010,335	964,603
Unbilled accounts receivable	130,888	107,010
Inventories and supplies	311,512	324,994
Prepaid expenses and other current assets	78,045	82,518
Total current assets	1,950,752	2,033,761
Property, plant and equipment, net	2,128,508	1,980,302
Other assets:
Operating lease right-of-use assets	188,695	166,181
Goodwill	1,286,473	1,246,878
Permits and other intangibles, net	613,540	620,782
Other	80,211	81,803
Total other assets	2,168,919	2,115,644
Total assets	6,248,179	6,129,707
Current liabilities:
Current portion of long-term debt	10,000	10,000
Accounts payable	414,963	446,629
Deferred revenue	102,468	94,094
Accrued expenses and other current liabilities	369,097	396,716
Current portion of closure, post-closure and remedial liabilities	21,759	23,123
Current portion of operating lease liabilities	57,100	49,532
Total current liabilities	975,387	1,020,094
Other liabilities:
Closure and post-closure liabilities, less current portion of $11,425 and $13,205, respectively	108,466	105,596
Remedial liabilities, less current portion of $10,334 and $9,918, respectively	101,370	106,372
Long-term debt, less current portion	2,292,952	2,414,828
Operating lease liabilities, less current portion	133,163	119,259
Deferred tax liabilities	347,628	350,389
Other long-term liabilities	103,419	90,847
Total other liabilities	3,086,998	3,187,291
Commitments and contingent liabilities (See Note 16)
Stockholders’ equity:
Common stock	541	541
Additional paid-in capital	490,163	504,240
Accumulated other comprehensive loss	(169,139)	(167,181)
Accumulated earnings	1,864,229	1,584,722
Total stockholders’ equity	2,185,794	1,922,322
Total liabilities and stockholders’ equity	$ 6,248,179	$ 6,129,707