Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 688,698	$ 1,036,455
Marketable securities	429,932	855,650
Accounts receivable, net of reserves of $1,078 and $1,534 at March 31, 2019, and December 31, 2018, respectively	529,346	479,889
Prepaid expenses and other current assets	170,442	163,360
Total current assets	1,818,418	2,535,354
Marketable securities	101,434	209,066
Property and equipment, net	951,259	910,618
Operating lease right-of-use assets	358,554
Acquired intangible assets, net	184,879	168,348
Goodwill	1,586,990	1,487,404
Deferred income tax assets	30,363	34,913
Other assets	150,865	116,067
Total assets	5,182,762	5,461,770
Current liabilities:
Accounts payable	102,371	99,089
Accrued expenses	238,524	328,304
Deferred revenue	110,667	69,083
Convertible senior notes	0	686,552
Operating lease liabilities	101,545
Other current liabilities	16,599	27,681
Total current liabilities	569,706	1,210,709
Deferred revenue	6,482	4,557
Deferred income tax liabilities	19,396	19,624
Convertible senior notes	883,584	874,080
Operating lease liabilities	293,381
Other liabilities	126,996	160,940
Total liabilities	1,899,545	2,269,910
Commitments and contingencies (Note 8)
Stockholders’ equity:
Preferred stock, $0.01 par value; 5,000,000 shares authorized; 700,000 shares designated as Series A Junior Participating Preferred Stock; no shares issued or outstanding	0	0
Common stock, $0.01 par value; 700,000,000 shares authorized; 163,995,208 shares issued and 163,503,258 shares outstanding at March 31, 2019, and 162,904,550 shares issued and outstanding at December 31, 2018	1,640	1,629
Additional paid-in capital	3,686,337	3,670,033
Accumulated other comprehensive loss	(46,979)	(48,912)
Treasury stock, at cost, 491,950 shares at March 31, 2019, and no shares at December 31, 2018	(34,872)	0
Accumulated deficit	(322,909)	(430,890)
Total stockholders’ equity	3,283,217	3,191,860
Total liabilities and stockholders’ equity	$ 5,182,762	$ 5,461,770