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 income	$ 64,975	$ 147,111	$ 137,861
Income (loss) from discontinued operations, net of income taxes	8,480	(38)	1,760
Income (loss) from continuing operations, net of income taxes	56,495	147,149	136,101
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	26,147	13,592	9,424
Stock-based compensation expense	7,327	9,703	12,549
Provision for deferred income taxes	1,015	5,618	28,765
Loss on foreign exchange hedge			3,489
Discounts on notes receivable	1,100
Gain on sale of central inverter service business	(14,795)
Net loss on disposal of assets	700	481	122
Changes in operating assets and liabilities, net of assets acquired:
Accounts and other receivable, net	(18,879)	3,445	(7,497)
Inventories	3,687	(11,276)	(19,261)
Other assets	23,544	(2,975)	(1,030)
Accounts payable	(16,094)	(12,618)	1,812
Other liabilities and accrued expenses	(12,486)	(3,239)	7,159
Income taxes	(9,862)	1,547	18,323
Net cash provided by (used in) operating activities from continuing operations	47,899	151,427	189,956
Net cash provided by (used in) operating activities from discontinued operations	493	(156)	(7,255)
Net cash provided by operating activities	48,392	151,271	182,701
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of marketable securities		(95)	(107)
Proceeds from sale of marketable securities	1,742	589	1,903
Acquisitions, net of cash acquired	(366,101)	(93,756)	(17,347)
Issuance of notes receivable	(4,300)
Purchase of foreign exchange hedge			(3,489)
Purchases of property and equipment	(25,188)	(20,330)	(9,042)
Net cash provided by (used in) investing activities from continuing operations	(393,847)	(113,592)	(28,082)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net proceeds from long-term borrowings	347,486
Payments on long-term borrowings	(8,750)
Purchase and retirement of common stock		(95,125)	(29,993)
Net payments related to stock-based award activities	104	(2,009)	(1,314)
Net cash provided by (used in) financing activities from continuing operations	338,840	(97,134)	(31,307)
EFFECT OF CURRENCY TRANSLATION ON CASH	(1,496)	(1,030)	2,208
INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	(8,111)	(60,485)	125,520
CASH AND CASH EQUIVALENTS, beginning of period	354,552	415,037	289,517
CASH AND CASH EQUIVALENTS, end of period	346,441	354,552	415,037
Less cash and cash equivalents from discontinued operations		5,251	7,754
CASH AND CASH EQUIVALENTS FROM CONTINUING OPERATIONS, end of period	346,441	349,301	407,283
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:
Cash paid for interest	3,479	228	66
Cash paid for income taxes	18,594	16,190	5,314
Cash received for refunds of income taxes	$ 1,762	$ 1,135	$ 1,448