CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net loss	$ (26,856)	$ (21,440)	$ (5,688)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	5,697	3,208	3,502
Depreciation and amortization	3,222	2,379	1,384
Amortization of intangible assets	7,153	3,871	1,222
Amortization of debt discount	6,408	1,125	82
Deferred income taxes	(372)	(184)	(1)
Prepayment premium and related costs of early extinguishment of debt	784
Gain on sale of equipment		(18)
Changes in fair value of earn-out liability	(320)	(2,569)
Impairment and other losses	1,694	2,680
Changes in assets and liabilities:
Accounts receivable	(17,281)	(11,331)	(2,557)
Inventories	(1,388)	(7,111)	(632)
Prepaid expenses and other current assets	238	1,539	(478)
Other non-current assets	260	(11)	(270)
Accounts payable	7,070	5,174	2,521
Accrued compensation and benefits	1,241	1,424	1,015
Accrued expenses and other current liabilities	2,959	(719)	58
Price adjustments and other revenue reserves	(1,179)	4,819
Other non-current liabilities	(1,181)	(58)	75
Deferred rent		(457)	(422)
Net cash used in operating activities	(11,851)	(17,679)	(189)
Cash flows from investing activities:
Acquisition of property and equipment	(4,517)	(3,208)	(2,868)
Maturities of short-term investments		1,274
Investment in unconsolidated affiliate	(457)	(566)	(334)
Net cash used in investing activities	(4,974)	(65,952)	(3,552)
Cash flows from financing activities:
Proceeds from public offering, net of underwriting discounts and commissions		42,659	18,363
Proceeds from exercise of stock options and employee stock purchase plan	1,571	830	781
Tax withholdings related to net share settlement of restricted stock units	(582)	(424)	(308)
Proceeds from revolving line of credit			30,598
Payments on revolving line of credit		(1,500)	(30,905)
Proceeds from term loan, net of fees		33,591	12,000
Proceeds from issuance of convertible senior notes, net of issuance costs	76,992
Payments on term loan	(35,492)	(12,292)	(16,364)
Purchase of capped calls	(6,150)
Payment on earn-out liability	(7,219)
Net cash provided by financing activities	29,120	62,864	14,165
Effect of exchange rates on cash, cash equivalents and restricted cash	339	(223)	(65)
Net increase (decrease) in cash, cash equivalents and restricted cash	12,634	(20,990)	10,359
Cash, cash equivalents and restricted cash - beginning of year	9,088	30,078	19,719
Cash, cash equivalents and restricted cash - end of year	21,722	9,088	30,078
Supplemental disclosures of other cash flow information:
Cash paid for interest expense	2,882	2,800	695
Supplemental disclosures of non-cash investing and financing information:
Purchase of property and equipment included in accounts payable	372	533	420
Fair value of warrants issued in connection with term loan		4,799	363
Accrued deferred financing costs			125
Equity component of convertible senior notes	$ 21,662
Echelon Corporation [Member]
Cash flows from investing activities:
payments to acquire businesses, net of cash acquired		(28,836)
S3 Asic Semiconductors Limited [Member]
Cash flows from investing activities:
payments to acquire businesses, net of cash acquired		$ (34,616)	$ (350)