CONSOLIDATED AND CONDENSED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities
Net loss	$ (208,509)	$ (95,414)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation and amortization	54,882	39,675
Equity based compensation	54,213	28,462
Amortization of discount and issuance costs on convertible notes	9,353	0
Other non-cash adjustments	133	868
Changes in operating assets and liabilities:
Accounts receivable	3,058	(4,723)
Inventories	(2,741)	3,949
Prepaid expenses and other current assets	(22,354)	(31,220)
Accounts payable and accrued expenses	95,743	(137)
Deferred revenue and other liabilities	52,211	30,660
Other assets	(1,462)	(117)
Net cash provided by (used in) operating activities	34,527	(27,997)
Cash flows from investing activities
Purchase of short-term and long-term investments	0	(25,334)
Sale and maturities of short-term investments	26,646	46,035
Purchase of property and equipment	(61,093)	(45,548)
Site and software development costs	(28,573)	(22,650)
Other investing activities	(267)	0
Net cash used in investing activities	(63,287)	(47,497)
Cash flows from financing activities
Taxes paid related to net share settlement of equity awards	(635)	(1,252)
Net proceeds from exercise of stock options	74	162
Net cash used in financing activities	(561)	(1,090)
Effect of exchange rate changes on cash and cash equivalents	(187)	554
Net decrease in cash and cash equivalents	(29,508)	(76,030)
Cash and cash equivalents
Beginning of period	558,960	279,840
End of period	529,452	203,810
Supplemental Cash Flow Information
Cash paid for interest on long-term debt	746	0
Purchase of property and equipment included in accounts payable and accrued expenses and in other liabilities	15,463	13,976
Construction costs capitalized under finance lease obligation and other leases	$ 54,143	$ 9,691