CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Cash flows from operating activities
Net income (loss)	$ 10,101	$ 23,753
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation expense	3,557	1,182
Share-based compensation	6,124	3,533
Changes in operating assets and liabilities:
Accounts receivable	(77,151)	(1,399)
Prepaid expenses	(1,976)	1,145
Other assets	(426)	0
Accounts payable	(355)	184
Accrued expenses	866	375
Lease exit liability	(2,134)	(2,383)
Deferred revenue	(3,179)	(7,812)
Deferred rent	(563)	(450)
Net cash provided by (used in) operating activities	(65,136)	18,128
Cash flows from investing activities
Purchases of marketable securities	(202,392)	0
Proceeds from sale and maturities of marketable securities	141,611	0
Purchases of property and equipment	(8,339)	(3,809)
Net cash used in investing activities	(69,120)	(3,809)
Cash flows from financing activities
Proceeds from issuance of common stock, net of offering costs	0	62,692
Proceeds from stock option exercises	351	425
Net cash provided by financing activities	351	63,117
Net change in cash and cash equivalents	(133,905)	77,436
Cash and cash equivalents at beginning of period	196,172	157,591
Cash and cash equivalents at end of period	$ 62,267	$ 235,027