CONSOLIDATED AND CONDENSED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash flows from operating activities
Net loss	$ (171,843)	$ (150,419)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation and amortization	62,588	38,528
Equity based compensation	46,740	35,188
Amortization of discount and issuance costs on convertible notes	874	0
Other non-cash adjustments	913	(134)
Changes in operating assets and liabilities:
Accounts receivable	(8,697)	(6,773)
Inventories	(38)	716
Prepaid expenses and other current assets	(27,776)	(12,493)
Accounts payable and accrued expenses	44,692	53,443
Deferred revenue and other liabilities	50,450	33,556
Other assets	(1,148)	(2,292)
Net cash used in operating activities	(3,245)	(10,680)
Cash flows from investing activities
Purchase of short-term and long-term investments	(47,639)	(76,458)
Sale and maturities of short-term investments	60,540	82,060
Purchase of property and equipment	(76,528)	(81,844)
Site and software development costs	(34,885)	(21,444)
Cash received from the sale of a business, net of cash sold	0	1,508
Other investing activities, net	0	(1,000)
Net cash used in investing activities	(98,512)	(97,178)
Cash flows from financing activities
Proceeds from issuance of convertible notes, net of issuance costs	420,449	0
Premiums paid for capped call confirmations	(44,160)	0
Taxes paid related to net share settlement of equity awards	(1,277)	(18,426)
Net proceeds from exercise of stock options	213	166
Net cash provided by (used in) financing activities	375,225	(18,260)
Effect of exchange rate changes on cash and cash equivalents	413	286
Net increase (decrease) in cash and cash equivalents	273,881	(125,832)
Cash and cash equivalents
Beginning of period	279,840	334,176
End of period	553,721	208,344
Supplemental disclosure of non-cash investing activities
Purchase of property and equipment included in accounts payable and accrued expenses and in other liabilities	9,255	5,744
Construction costs capitalized under finance lease obligation and other leases	$ 16,153	$ 29,726