CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 547,993	$ 449,511
Marketable securities, short-term	164,629	272,031
Accounts receivable, net of allowance for doubtful accounts of $2,729 and $5,814, respectively	374,371	324,189
Inventories	47,252	31,688
Prepaid expenses and other current assets	126,754	80,948
Total current assets	1,260,999	1,158,367
Marketable securities, long-term	8,061	39,948
Property, plant and equipment, net	447,933	348,793
Equity method investments	49,128	54,606
Goodwill and intangible assets, net	85,307	89,068
Deferred tax assets	45,859	49,334
Other assets	19,302	43,893
Total assets	1,916,589	1,784,009
Current liabilities:
Accounts payable	48,744	36,776
Accrued liabilities	196,754	195,562
Deferred revenues	321,148	267,713
Total current liabilities	566,646	500,051
Income tax payable	115,701	114,091
Other long-term liabilities	15,283	15,579
Total liabilities	697,630	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; 80,313 and 80,040 issued and outstanding, respectively)	8	8
Additional paid-in capital	844,599	886,435
Accumulated other comprehensive income (loss), net	911	571
Retained earnings	373,441	267,274
Total stockholders’ equity	1,218,959	1,154,288
Total liabilities and stockholders’ equity	$ 1,916,589	$ 1,784,009