Condensed Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	3 Months Ended					9 Months Ended		12 Months Ended
	Sep. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Cash flows from operating activities:
Net income	$ 68,347	$ 28,214		$ 35,809	$ 34,366	$ 109,747	$ 117,702
Adjustments to reconcile net income to cash flows provided by operating activities:
Depreciation and amortization						73,366	55,882
Stock-based compensation expense						13,646	12,061
Other non-cash items						1,818	837
Changes in assets and liabilities, net of acquisitions of businesses:
Accounts receivable, net						(103,209)	(42,367)
Inventories, net						24,423	24,410
Prepaid expenses and other assets						(29,489)	15,119
Accounts payable, trade						68,379	8,437
Accrued expenses and other liabilities						53,806	17,461
Net cash flows provided by operating activities						212,487	209,542
Cash flows from investing activities:
Capital expenditures						(28,663)	(47,767)
Acquisitions of businesses, net of cash acquired						(94,909)	(53,923)
Other investing activities						3,972	364
Net cash flows used in investing activities						(119,600)	(101,326)
Cash flows from financing activities:
Vesting of stock-based awards, net of shares tendered for payment of taxes						(4,807)	(7,194)
Proceeds from revolving credit facility						285,827	404,228
Repayments under revolving credit facility						(273,130)	(443,921)
Repayments under term loan and other borrowings						(15,385)	0
Payment of dividends						(51,535)	(47,533)
Other financing activities						(176)	(405)
Net cash flows used in financing activities						(59,206)	(94,825)
Effect of exchange rate changes on cash, cash equivalents, and restricted cash						(853)	(842)
Net increase in cash, cash equivalents, and restricted cash						32,828	12,549
Cash, cash equivalents, and restricted cash at beginning of period		$ 35,359	$ 27,477		$ 14,928	35,359	14,928	$ 14,928
Cash, cash equivalents, and restricted cash at end of period	$ 68,187		$ 35,359	$ 27,477		68,187	27,477	$ 35,359
Supplemental disclosure of cash flow information:
Cash paid during the period for interest						12,743	6,156
Cash paid during the period for income taxes, net of refunds						16,457	28,416
Purchase of property and equipment in accrued expenses						$ 2,588	$ 588