Condensed Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash flows from operating activities:
Net income	$ 128,372	$ 115,420
Adjustments to reconcile net income to cash flows provided by operating activities:
Depreciation and amortization	49,739	39,856
Stock-based compensation expense	13,852	15,042
Other non-cash items	(959)	3,655
Changes in assets and liabilities, net of acquisitions of businesses:
Accounts receivable, net	(51,733)	(69,720)
Inventories, net	(16,475)	(33,780)
Prepaid expenses and other assets	(9,506)	(18,662)
Accounts payable, trade	(12,930)	29,856
Accrued expenses and other liabilities	7,232	26,147
Net cash flows provided by operating activities	107,592	107,814
Cash flows from investing activities:
Capital expenditures	(92,522)	(60,342)
Acquisitions of businesses, net of cash acquired	(156,701)	(67,876)
Proceeds from note receivable	2,000	0
Other investing activities	(875)	243
Net cash flows used in investing activities	(248,098)	(127,975)
Cash flows from financing activities:
Exercise of stock-based awards, net of shares tendered for payment of taxes	(14,114)	(7,313)
Proceeds from line of credit borrowings	928,601	9,715
Repayments under line of credit borrowings	(738,601)	(9,715)
Proceeds from other borrowings	4,509	0
Payment of dividends	44,114	37,346
Payment of contingent consideration related to acquisitions	(3,018)	(1,529)
Other financing activities	(556)	(59)
Net cash flows provided by (used in) financing activities	132,707	(46,247)
Net decrease in cash and cash equivalents	(7,799)	(66,408)
Cash and cash equivalents at beginning of period	26,049	86,170
Cash and cash equivalents at end of period	18,250	19,762
Supplemental disclosure of cash flow information:
Cash paid during the period for interest	4,244	1,291
Cash paid during the period for income taxes, net of refunds	33,844	48,181
Purchase of property and equipment in accrued expenses	$ 467	$ 1,205