CONDENSED CONSOLIDATED STATEMENT OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Cash flows from operating activities:
Net loss	$ (75,076)	$ (131,957)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	69,314	63,435
Amortization of intangible assets	15,744	20,798
Amortization of debt discount and transaction costs	10,747	10,163
Stock-based compensation	33,288	49,831
Loss on disposal of property and equipment	378	1,475
Deferred income taxes	5,786	(14,414)
Tax benefit from stock-based compensation	263	13,041
Excess tax benefits from stock-based compensation	(886)	(13,666)
Changes in operating assets and liabilities:
Accounts receivable	10,463	(17,797)
Inventories	2,115	1,406
Prepaid expenses and other assets	(61,113)	(12,146)
Accounts payable	(15,105)	(14,157)
Accrued and other liabilities	(67,806)	(63,712)
Net cash used in operating activities	(71,888)	(107,700)
Cash flows from investing activities:
Purchases of property and equipment	(43,733)	(46,448)
Capitalization of software and website development costs	(27,136)	(15,448)
Purchases of investments	(21,891)	(4,400)
Proceeds from the maturities and sales of investments	25,070	52,460
Proceeds from sale of property and equipment	14,071	1,128
Acquisition of business and intangible assets, net of cash acquired	0	(127)
Net cash used in investing activities	(53,619)	(12,835)
Cash flows from financing activities:
Proceeds from issuance of common stock upon exercise of stock options	1,935	2,670
Repurchases of common stock	(90,837)	(134,084)
Prepayment of accelerated share repurchase	0	(75,000)
Refund of accelerated share repurchase	0	38,179
Excess tax benefits from stock-based compensation	886	13,666
Principal payments of capital lease and financing obligations	(15,128)	(8,988)
Net cash used in financing activities	(103,144)	(163,557)
Net decrease in cash and cash equivalents	(228,651)	(284,092)
Cash and cash equivalents, beginning of period	288,863	380,543
Cash and cash equivalents, end of period	60,212	96,451
Supplemental schedule of non-cash investing / financing activities:
Net increase (decrease) in accrued purchases of property and equipment	(1,274)	(154)
Net increase (decrease) in accrued capitalized software and website development costs	(97)	363
Stock-based compensation capitalized with software and website development costs	1,322	1,001
Increase in estimated fair market value of buildings under build-to-suit leases	0	17,161
Property and equipment acquired under capital leases	$ 23,946	$ 29,097