CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash flows from operating activities:
Net income	$ 21,862	$ 18,167
Adjustments to reconcile net income to net cash used in operating activities:
Depreciation and amortization	2,616	2,619
Provision for doubtful accounts	165	225
Noncash share-based compensation	513	507
Deferred tax benefit	(258)	(406)
Change in fair value of derivatives	215	(285)
Changes in:
Accounts receivable	(42,959)	(33,983)
Inventories	(1,178)	(13,274)
Other assets	(1,200)	(743)
Accounts payable and accrued expenses	(6,984)	(563)
Income taxes, net	6,552	4,733
Net cash used in operating activities	(20,656)	(23,003)
Cash flows from investing activities:
Purchases of short-term investments	(9,979)	(24,310)
Proceeds from sale of short-term investments		4,259
Purchases of equipment and leasehold improvements	(580)	(729)
Payment for intangible assets acquired	(1,352)	(129)
Net cash used in investing activities	(11,911)	(20,909)
Cash flows from financing activities:
Repayment of long-term debt	(6,140)	(5,250)
Proceeds from exercise of options	1,003	542
Dividends paid	(6,561)	(5,293)
Dividends paid to minority interest	(362)
Net cash used in financing activities	(12,060)	(10,001)
Effect of exchange rate changes on cash	5,213	1,914
Net decrease in cash and cash equivalents	(39,414)	(51,999)
Cash and cash equivalents - beginning of period	208,343	161,828
Cash and cash equivalents - end of period	168,929	109,829
Cash paid for:
Interest	420	492
Income taxes	$ 5,306	$ 4,576