Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 515,896	$ 1,036,455
Marketable securities	526,596	855,650
Accounts receivable, net of reserves of $1,612 and $1,534 at June 30, 2019, and December 31, 2018, respectively	523,382	479,889
Prepaid expenses and other current assets	178,920	163,360
Total current assets	1,744,794	2,535,354
Marketable securities	287,046	209,066
Property and equipment, net	1,019,407	910,618
Operating lease right-of-use assets	359,128
Acquired intangible assets, net	176,031	168,348
Goodwill	1,586,642	1,487,404
Deferred income tax assets	19,677	34,913
Other assets	150,511	116,067
Total assets	5,343,236	5,461,770
Current liabilities:
Accounts payable	126,539	99,089
Accrued expenses	250,015	328,304
Deferred revenue	110,750	69,083
Convertible senior notes	0	686,552
Operating lease liabilities	96,160
Other current liabilities	7,350	27,681
Total current liabilities	590,814	1,210,709
Deferred revenue	5,204	4,557
Deferred income tax liabilities	25,099	19,624
Convertible senior notes	893,191	874,080
Operating lease liabilities	299,062
Other liabilities	135,102	160,940
Total liabilities	1,948,472	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; 164,906,403 shares issued and 163,359,091 shares outstanding at June 30, 2019, and 162,904,550 shares issued and outstanding at December 31, 2018	1,649	1,629
Additional paid-in capital	3,760,840	3,670,033
Accumulated other comprehensive loss	(42,484)	(48,912)
Treasury stock, at cost, 1,547,312 shares at June 30, 2019, and no shares at December 31, 2018	(116,247)	0
Accumulated deficit	(208,994)	(430,890)
Total stockholders’ equity	3,394,764	3,191,860
Total liabilities and stockholders’ equity	$ 5,343,236	$ 5,461,770