CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 420,860	$ 449,511
Marketable securities, short-term	184,297	272,031
Accounts receivable, net of allowance for doubtful accounts of $2,611 and $5,814, respectively	420,276	324,189
Inventories	48,858	31,688
Prepaid expenses and other current assets	149,891	80,948
Total current assets	1,224,182	1,158,367
Marketable securities, long-term	8,091	39,948
Property, plant and equipment, net	491,630	348,793
Equity method investments	47,996	54,606
Goodwill and intangible assets, net	83,607	89,068
Deferred tax assets	47,435	49,334
Other assets	25,464	43,893
Total assets	1,928,405	1,784,009
Current liabilities:
Accounts payable	43,065	36,776
Accrued liabilities	219,035	195,562
Deferred revenues	356,109	267,713
Total current liabilities	618,209	500,051
Income tax payable	95,655	114,091
Other long-term liabilities	21,558	15,579
Total liabilities	735,422	629,721
Commitments and contingencies (Notes 8 and 9)
Stockholders' equity:
Preferred stock, $0.0001 par value (5,000 shares authorized; none issued)	0	0
Common stock, $0.0001 par value (200,000 shares authorized; 79,983 and 80,040 issued and outstanding, respectively)	8	8
Additional paid-in capital	865,271	886,435
Accumulated other comprehensive income (loss), net	(728)	571
Retained earnings	328,432	267,274
Total stockholders’ equity	1,192,983	1,154,288
Total liabilities and stockholders’ equity	$ 1,928,405	$ 1,784,009