Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 2,023,808	$ 1,412,517
Short-term investments	27,033	28,271
Accounts receivable, net of allowance for doubtful accounts of $19,173 and $18,228	645,468	576,313
Other current assets	247,175	232,027
Total current assets	2,943,484	2,249,128
Long-term investments	12,173	9,243
Property, plant and equipment, net	9,696,692	9,394,602
Goodwill	4,485,155	4,411,762
Intangible assets, net	2,356,608	2,384,972
Other assets	447,816	241,750
Total assets	19,941,928	18,691,457
Current liabilities:
Accounts payable and accrued expenses	686,612	719,257
Accrued property, plant and equipment	257,813	220,367
Current portion of capital lease and other financing obligations	77,386	78,705
Current portion of mortgage and loans payable	79,699	64,491
Other current liabilities	144,965	159,914
Total current liabilities	1,246,475	1,242,734
Capital lease and other financing obligations, less current portion	1,629,597	1,620,256
Mortgage and loans payable, less current portion	1,416,538	1,393,118
Senior notes	7,900,611	6,923,849
Other liabilities	608,156	661,710
Total liabilities	12,801,377	11,841,667
Commitments and contingencies (Note 9)
Stockholders' equity:
Common stock, $0.001 par value per share: 300,000,000 shares authorized; 79,457,531 and 79,038,062 shares outstanding	80	79
Additional paid-in capital	10,193,030	10,121,323
Treasury stock, at cost; 399,385 and 402,342 shares	(145,695)	(146,320)
Accumulated dividends	(2,776,178)	(2,592,792)
Accumulated other comprehensive loss	(718,169)	(785,189)
Retained earnings	587,483	252,689
Total stockholders' equity	7,140,551	6,849,790
Total liabilities and stockholders' equity	$ 19,941,928	$ 18,691,457