Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016		Mar. 31, 2015
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 15,901		$ 9,686
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	4,801		4,629
Provision for warranty and returns	39		31
Stock compensation	3,808		2,813
(Gain) loss on disposal of property and equipment	(1)		2
Bond premium amortization	528		943
Cash provided by (used in) changes in operating assets and liabilities
Accounts receivable	2,552		(4,947)
Inventories	(4,866)		(1,785)
Prepaid expenses and other assets	(3,474)		(980)
Accounts payable	(1,383)		1,951
Accrued liabilities	(8,014)		3,300
Income taxes, including excess tax benefits and deferred income taxes	4,893		(2,392)
Net cash provided by operating activities	14,784		13,251
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(3,963)		(2,357)
Proceeds from sale of asset	1		0
Intangible assets additions	(219)		(208)
Purchases of investment securities	(7,061)		(9,205)
Proceeds from sale of investment securities	11,802		31,785
Net cash provided by investing activities	560		20,015
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from exercise of stock options	5,421		4,777
Proceeds from employee stock purchase plan	1,197		1,041
Tax benefits from exercise of stock options	2,511		3,059
Purchase of treasury stock	(16,897)		(1,435)
Net cash (used in) provided by financing activities	(7,768)		7,442
Effect of exchange rate changes on cash	3,630		(7,987)
NET INCREASE IN CASH AND CASH EQUIVALENTS	11,206		32,721
CASH AND CASH EQUIVALENTS, beginning of period	336,164	[1]	275,812
CASH AND CASH EQUIVALENTS, end of period	347,370		308,533
NON-CASH INVESTING ACTIVITIES
Accrued liabilities for property and equipment	$ 522		$ 144

[1] December 31, 2015 balances were derived from audited consolidated financial statements.