Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 536,725	$ 352,917
Marketable securities	541,470	745,156
Accounts receivable, net of reserves of $1,397 and $1,822 at December 31, 2021 and 2020, respectively	675,926	660,052
Prepaid expenses and other current assets	166,313	171,406
Total current assets	1,920,434	1,929,531
Marketable securities	1,088,048	1,398,802
Property and equipment, net	1,534,329	1,478,272
Operating lease right-of-use assets	815,754	793,945
Acquired intangible assets, net	313,225	234,724
Goodwill	2,156,254	1,674,371
Deferred income tax assets	168,342	106,918
Other assets	142,287	147,567
Total assets	8,138,673	7,764,130
Current liabilities:
Accounts payable	109,928	118,546
Accrued expenses	411,590	380,468
Deferred revenue	86,517	76,600
Operating lease liabilities	175,683	154,801
Other current liabilities	6,623	27,755
Total current liabilities	790,341	758,170
Deferred revenue	25,342	5,262
Deferred income tax liabilities	40,974	37,458
Convertible senior notes	1,976,167	1,906,707
Operating lease liabilities	707,087	715,404
Other liabilities	68,748	89,833
Total liabilities	3,608,659	3,512,834
Commitments and contingencies (Note 13)
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; 160,512,111 and 162,709,720 shares issued and outstanding at December 31, 2021 and 2020, respectively	1,605	1,627
Additional paid-in capital	3,340,822	3,664,820
Accumulated other comprehensive loss	(69,105)	(20,201)
Retained earnings	1,256,692	605,050
Total stockholders’ equity	4,530,014	4,251,296
Total liabilities and stockholders’ equity	$ 8,138,673	$ 7,764,130