CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 238,776	$ 492,603
Short-term marketable securities	87,346	62,033
Accounts receivable, net of allowances aggregating $43,393 and $45,253, respectively	981,233	964,603
Unbilled accounts receivable	122,679	107,010
Inventories and supplies	325,882	324,994
Prepaid expenses and other current assets	92,559	82,518
Total current assets	1,848,475	2,033,761
Property, plant and equipment, net	2,082,693	1,980,302
Other assets:
Operating lease right-of-use assets	181,243	166,181
Goodwill	1,288,291	1,246,878
Permits and other intangibles, net	626,320	620,782
Other	74,315	81,803
Total other assets	2,170,169	2,115,644
Total assets	6,101,337	6,129,707
Current liabilities:
Current portion of long-term debt	10,000	10,000
Accounts payable	374,438	446,629
Deferred revenue	105,327	94,094
Accrued expenses and other current liabilities	348,857	396,716
Current portion of closure, post-closure and remedial liabilities	21,802	23,123
Current portion of operating lease liabilities	53,991	49,532
Total current liabilities	914,415	1,020,094
Other liabilities:
Closure and post-closure liabilities, less current portion of $12,186 and $13,205, respectively	108,522	105,596
Remedial liabilities, less current portion of $9,616 and $9,918, respectively	102,560	106,372
Long-term debt, less current portion	2,294,306	2,414,828
Operating lease liabilities, less current portion	129,058	119,259
Deferred tax liabilities	346,328	350,389
Other long-term liabilities	96,262	90,847
Total other liabilities	3,077,036	3,187,291
Commitments and contingent liabilities (See Note 16)
Stockholders’ equity:
Common stock	541	541
Additional paid-in capital	502,422	504,240
Accumulated other comprehensive loss	(165,966)	(167,181)
Accumulated earnings	1,772,889	1,584,722
Total stockholders’ equity	2,109,886	1,922,322
Total liabilities and stockholders’ equity	$ 6,101,337	$ 6,129,707