CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities
Net income	$ 243,700	$ 223,400	$ 118,800
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization of property and equipment	52,200	47,300	43,600
Amortization of operating lease right-of-use assets	29,000	26,600	22,300
Amortization of intangibles	44,500	43,800	37,100
Amortization of deferred financing costs and debt discount	1,900	1,900	1,400
Provision for credit losses	6,300	4,100	2,200
Write-off of debt issuance costs	900	0	1,800
Gain on sale of property and equipment	(1,900)	(1,400)	(1,800)
Noncash stock compensation	15,900	13,800	13,800
Gains on acquisition earnouts	0	(16,100)	(1,100)
Deferred income taxes	500	7,100	(400)
Other, net	(12,200)	(100)	3,200
Changes in assets and liabilities, excluding effects of acquisitions
Accounts receivable	(25,100)	(76,500)	(16,800)
Inventories	16,500	(16,500)	(54,000)
Proceeds from termination of interest rate swap agreements	0	25,500	0
Other assets	(11,000)	(2,600)	(19,900)
Accounts payable	5,100	9,600	26,400
Income taxes receivable/payable	(5,700)	3,200	(4,500)
Other liabilities	(20,400)	(15,200)	(33,800)
Net cash provided by operating activities	340,200	277,900	138,300
Cash flows from investing activities
Purchases of investments	0	(344,400)	0
Maturities of short term investments	0	345,000	0
Purchases of property and equipment	(61,600)	(45,600)	(37,000)
Acquisitions of businesses, net of cash acquired of $—, $0.5 and $1.7 in 2023, 2022 and 2021, respectively	(59,600)	(113,500)	(241,300)
Proceeds from sale of property and equipment	2,700	2,000	2,700
Settlements with interest rate swap counterparties	16,700	4,000	0
Other, net	(1,600)	(6,200)	(2,800)
Net cash used in investing activities	(103,400)	(158,700)	(278,400)
Cash flows from financing activities
Proceeds from term loan (Note 8)	0	0	500,000
Payments on term loan (Note 8)	(5,000)	(5,000)	(200,000)
Proceeds from vehicle and equipment notes payable	38,700	30,900	27,800
Debt issuance costs	(500)	(600)	(7,500)
Principal payments on long-term debt	(29,500)	(30,200)	(26,300)
Principal payments on finance lease obligations	(2,900)	(2,300)	(2,100)
Acquisition-related obligations	(4,700)	(11,100)	(8,900)
Dividends paid	(63,100)	(62,700)	(35,300)
Repurchase of common stock	(6,300)	(137,600)	0
Surrender of common stock awards by employees	(6,600)	(4,500)	(5,600)
Net cash (used in) provided by financing activities	(79,900)	(223,100)	242,100
Net change in cash and cash equivalents	156,900	(103,900)	102,000
Cash and cash equivalents at beginning of period	229,600	333,500	231,500
Cash and cash equivalents at end of period	386,500	229,600	333,500
Supplemental disclosures of cash flow information
Interest	42,500	40,300	26,000
Income taxes, net of refunds	92,500	69,100	39,200
Supplemental disclosure of noncash activities
Right-of-use assets obtained in exchange for operating lease obligations	30,700	32,700	38,100
Release of indemnification of acquisition-related debt	0	1,000	2,000
Property and equipment obtained in exchange for finance lease obligations	3,300	6,200	2,700
Seller obligations in connection with acquisition of businesses	9,300	27,000	29,200
Unpaid purchases of property and equipment included in accounts payable	$ 3,100	$ 900	$ 400