Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Operating Activities
Net income	$ 31,555	$ 37,110
Adjustments to reconcile net income to net cash used in operating activities:
Depreciation and amortization	3,425	4,765
Stock-based compensation	2,793	2,295
Loss (Gain) on disposal of property, plant and equipment	10	(22)
Changes in operating assets and liabilities:
Accounts receivable	(128,182)	(139,643)
Inventories	7,645	(7,928)
Prepaid expenses and other assets	1,214	118
Accounts payable	(7,556)	13,770
Accrued expenses and other liabilities	(27,332)	(18,972)
Income taxes receivable/payable	6,438	10,399
Net cash used in operating activities	(109,990)	(98,108)
Investing Activities
Expenditures for property, plant and equipment and intangibles	(8,647)	(5,435)
Proceeds from sales of property, plant and equipment	0	24
Net cash used in investing activities	(8,647)	(5,411)
Financing Activities
Borrowings under line of credit	35,000	92,500
Principal payments under line of credit	0	(8,000)
Repurchases of common stock	(14,457)	(8,993)
Proceeds from employee stock purchase and option plans	302	197
Net cash provided by financing activities	20,845	75,704
Net decrease in cash and cash equivalents	(97,792)	(27,815)
Cash and cash equivalents, beginning of period	105,699	30,514
Cash and cash equivalents, end of period	7,907	2,699
Supplemental Disclosure:
Cash paid for interest	11	62
Cash paid (received) for income taxes, net	$ 1,262	$ (21)