Condensed Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash flows from operating activities:
Net income	$ 115,420	$ 103,372
Adjustments to reconcile net income to cash flows provided by operating activities:
Depreciation and amortization	39,856	33,720
Stock-based compensation expense	15,042	11,421
Deferred taxes	0	183
Other non-cash items	3,655	1,728
Changes in assets and liabilities, net of acquisitions of businesses:
Accounts receivable, net	(69,720)	(46,028)
Inventories, net	(33,780)	13,451
Prepaid expenses and other assets	(18,662)	(7,659)
Accounts payable, trade	29,856	23,827
Accrued expenses and other liabilities	27,192	30,093
Net cash flows provided by operating activities	108,859	164,108
Cash flows from investing activities:
Capital expenditures	(60,342)	(21,927)
Acquisitions of businesses, net of cash acquired	(67,876)	(34,237)
Proceeds from sales of fixed assets	348	533
Other investing activities	(105)	(316)
Net cash flows used for investing activities	(127,975)	(55,947)
Cash flows from financing activities:
Exercise of stock-based awards, net of shares tendered for payment of taxes	(7,313)	409
Proceeds from line of credit borrowings	9,715	81,458
Repayments under line of credit borrowings	(9,715)	(81,458)
Payment of dividends	37,346	22,078
Payment of contingent consideration related to acquisitions	(2,574)	(2,719)
Other financing activities	(59)	(1,018)
Net cash flows used for financing activities	(47,292)	(25,406)
Net (decrease) increase in cash and cash equivalents	(66,408)	82,755
Cash and cash equivalents at beginning of period	86,170	12,305
Cash and cash equivalents at end of period	19,762	95,060
Supplemental disclosure of cash flow information:
Cash paid during the period for interest	1,291	1,525
Cash paid during the period for income taxes, net of refunds	48,181	51,524
Purchase of property and equipment in accrued expenses	$ 1,205	$ 279