CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 355,345	$ 184,708
Accounts receivable, net of allowances aggregating $28,628 and $31,426, respectively	458,301	496,004
Unbilled accounts receivable	31,805	25,940
Deferred costs	19,346	18,758
Inventories and supplies	154,768	149,521
Prepaid expenses and other current assets	44,056	46,265
Total current assets	1,063,621	921,196
Property, plant and equipment, net	1,596,872	1,532,467
Other assets:
Deferred financing costs	1,627	1,847
Goodwill	460,642	453,105
Permits and other intangibles, net	502,532	506,818
Other	16,381	15,995
Total other assets	981,182	977,765
Total assets	3,641,675	3,431,428
Current liabilities:
Accounts payable	188,834	241,183
Deferred revenue	63,587	61,882
Accrued expenses	191,592	193,660
Current portion of closure, post-closure and remedial liabilities	21,497	20,395
Total current liabilities	465,510	517,120
Other liabilities:
Closure and post-closure liabilities, less current portion of $7,194 and $7,229, respectively	50,896	49,020
Remedial liabilities, less current portion of $14,303 and $13,166, respectively	117,076	118,826
Long-term obligations	1,631,603	1,382,543
Deferred taxes, unrecognized tax benefits and other long-term liabilities	260,017	267,637
Total other liabilities	$ 2,059,592	$ 1,818,026
Commitments and contingent liabilities
Stockholders’ equity:
Common Stock, $.01 par value: Authorized 80,000,000; shares issued and outstanding 57,551,188 and 57,593,201 shares, respectively	$ 576	$ 576
Shares held under employee participation plan	(469)	(469)
Additional paid-in capital	733,726	738,401
Accumulated other comprehensive loss	(209,055)	(254,892)
Accumulated earnings	591,795	612,666
Total stockholders’ equity	1,116,573	1,096,282
Total liabilities and stockholders’ equity	$ 3,641,675	$ 3,431,428