Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 966,308	$ 1,412,517
Short-term investments	18,199	28,271
Accounts receivable, net of allowance for doubtful accounts of $16,881 and $18,228	616,472	576,313
Other current assets	249,846	232,027
Total current assets	1,850,825	2,249,128
Long-term investments	4,200	9,243
Property, plant and equipment, net	10,378,915	9,394,602
Goodwill	4,870,300	4,411,762
Intangible assets, net	2,440,087	2,384,972
Other assets	525,961	241,750
Total assets	20,070,288	18,691,457
Current liabilities:
Accounts payable and accrued expenses	710,584	719,257
Accrued property, plant and equipment	269,409	220,367
Current portion of capital lease and other financing obligations	85,263	78,705
Current portion of mortgage and loans payable	75,224	64,491
Current portion of senior notes	150,828	0
Other current liabilities	142,312	159,914
Total current liabilities	1,433,620	1,242,734
Capital lease and other financing obligations, less current portion	1,426,368	1,620,256
Mortgage and loans payable, less current portion	1,317,940	1,393,118
Senior notes, less current portion	8,334,383	6,923,849
Other liabilities	633,450	661,710
Total liabilities	13,145,761	11,841,667
Commitments and contingencies (Note 9)
Stockholders' equity:
Common stock, $0.001 par value per share: 300,000,000 shares authorized; 79,507,996 and 79,038,062 shares outstanding	80	79
Additional paid-in capital	10,253,155	10,121,323
Treasury stock, at cost; 399,088 and 402,342 shares	(145,632)	(146,320)
Accumulated dividends	(2,960,183)	(2,592,792)
Accumulated other comprehensive loss	(877,994)	(785,189)
Retained earnings	655,101	252,689
Total stockholders' equity	6,924,527	6,849,790
Total liabilities and stockholders' equity	$ 20,070,288	$ 18,691,457