Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Statement of Cash Flows [Abstract]
Net loss	$ (38,425)	$ (15,677)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	13,182	10,818
Deferred income taxes	127	(120)
Bad debt expense and other reserves	485	811
Stock-based compensation	24,191	18,069
Increase in the fair value of contingent consideration liability	150	0
Amortization of lease right-of-use assets	2,944	0
Loss from equity method investment	273	0
Non-cash interest expense on lease financing obligation	0	218
Impairment or write-off and loss on disposal of finite-lived assets	1,139	143
Changes in operating assets and liabilities:
Accounts receivable	(2,011)	(4,491)
Prepaid expenses	(2,538)	(2,882)
Other current assets	(29,711)	(787)
Other assets	1,406	(835)
Accounts payable	(5,777)	(232)
Accrued employee expenses	5,905	106
Operating lease liabilities	(3,064)	0
Accrued expenses and other liabilities	39,047	3,033
Other liabilities	(99)	393
Net cash provided by operating activities	7,224	8,567
Cash flows from investing activities
Purchase of property and equipment	(5,405)	(9,615)
Cash paid for equity method investment	(23,174)	0
Net cash used in investing activities	(28,579)	(9,615)
Cash flows from financing activities
Proceeds from exercise of common stock options	2,835	3,196
Taxes paid related to net share settlement of equity awards	(1,043)	(1,423)
Net cash provided by financing activities	1,792	1,773
Net (decrease) increase in cash and cash equivalents	(19,563)	725
Cash and cash equivalents at beginning of period	196,128	197,762
Cash and cash equivalents at end of period	176,565	198,487
Supplemental disclosures of non-cash activities
Stock-based compensation capitalized for software development	978	807
Capitalized assets included in accounts payable, accrued employee expenses and other accrued expenses	245	554
Proceeds receivable from exercise of stock options included in other current assets	0	1
Taxes payable related to net share settlement of equity awards included in accrued employee expenses	$ 0	$ 29