Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Operating activities
Net loss	$ (76,582)	$ (12,135)
Adjustments to reconcile net loss to net cash used in operating activities:
Non-cash benefit on release of tax valuation allowance		(11,797)
Depreciation and amortization	3,509	1,017
Stock-based compensation expense	21,482	4,843
Change in fair value of contingent consideration	2,188
Other non-cash items	269	168
Changes in operating assets and liabilities:
Prepaid expenses and other assets	(1,059)	854
Accounts payable	(418)	(2,702)
Accrued expenses and other liabilities	1,098	7,674
Deferred revenue	13,716	(12,670)
Deferred rent	(480)	1,490
Net cash used in operating activities	(36,277)	(23,258)
Investing activities
Restricted cash	359
Purchase of property and equipment	(2,568)	(4,534)
Acquisition of business, net of cash acquired		(4,673)
Purchases of marketable securities	(261,440)
Proceeds from maturities of marketable securities	62,680
Net cash used in investing activities	(200,969)	(9,207)
Financing activities
Proceeds from public offering of common stock, net of issuance costs	477,179
Proceeds from issuance of common stock	5,521	1,896
Net cash provided by financing activities	482,700	1,896
Increase (decrease) in cash and cash equivalents	245,454	(30,569)
Cash and cash equivalents at beginning of period	347,845	206,279
Cash and cash equivalents at end of period	593,299	175,710
Non-cash investing and financing activities:
Assets acquired in acquisition		43,759
Liabilities assumed in acquisition		12,768
Equity issued in acquisition		19,348
Purchases of property and equipment included in accounts payable and accrued expenses	524	344
Offering expenses included in accounts payable and accrued expenses	115	45
Stock option exercise proceeds receivable	$ 181	$ 75