Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net income	$ 146,509	$ 148,551	$ 132,884
Adjustments to reconcile net income to cash flows provided by operating activities:
Depreciation and amortization	75,358	67,526	54,727
Stock-based compensation expense	16,077	14,065	20,036
Deferred taxes	3,416	13,874	6,808
Other non-cash items	(1,553)	(13)	4,371
Changes in assets and liabilities, net of acquisitions of businesses:
Accounts receivable, net	(25,452)	(11,352)	(12,601)
Inventories, net	57,790	(34,730)	(78,698)
Prepaid expenses and other assets	6,882	(17,691)	(10,898)
Accounts payable, trade	(12,189)	(17,335)	20,727
Accrued expenses and other liabilities	2,687	(6,287)	15,346
Net cash flows provided by operating activities	269,525	156,608	152,702
Cash flows from investing activities:
Capital expenditures	(58,202)	(119,827)	(87,221)
Acquisitions of businesses, net of cash acquired	(447,764)	(184,792)	(60,588)
Other investing activities	2,132	1,824	1,934
Net cash flows used in investing activities	(503,834)	(302,795)	(145,875)
Cash flows from financing activities:
Exercise of stock-based awards, net of shares tendered for payment of taxes	(8,084)	(16,097)	(10,531)
Proceeds from line of credit borrowings	655,387	1,387,013	28,130
Repayments under line of credit borrowings	(628,891)	(1,146,953)	(28,130)
Proceeds from term loan borrowings	300,000	0	0
Proceeds from other borrowings	0	4,509	0
Payment of dividends	(63,813)	(59,270)	(51,057)
Payment of contingent consideration related to acquisitions	(10)	(3,068)	(5,301)
Repurchases of common stock	0	(28,695)	0
Other financing activities	382	(2,373)	(59)
Net cash flows provided by (used in) financing activities	254,971	135,066	(66,948)
Effect of exchange rate changes on cash and cash equivalents	(231)	0	0
Net increase (decrease) in cash and cash equivalents	20,431	(11,121)	(60,121)
Cash and cash equivalents at beginning of period	14,928	26,049	86,170
Cash and cash equivalents at end of period	35,359	14,928	26,049
Supplemental disclosure of cash flow information:
Cash paid during the period for interest	9,143	5,645	1,650
Cash paid during the period for income taxes, net of refunds	37,836	39,991	53,620
Purchase of property and equipment in accrued expenses	$ 3,417	$ 385	$ 2,640