CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities
Net income	$ 65,651	$ 56,049
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation expense	30,265	25,739
Amortization of intangible assets	10,029	8,685
Amortization of debt issuance costs	634	807
Deferred income taxes	10,406	6,888
Non-cash stock compensation expense	6,498	6,163
Gain on sale of property, equipment and real estate	(351)	(1,949)
Other non-cash adjustments	2,248	2,200
Change in assets and liabilities, net of effects of acquisitions
Accounts receivable, net of allowances	(36,201)	(30,725)
Inventories	5,175	(8,557)
Accounts payable	49,401	85,178
Other assets and liabilities	9,412	(21,166)
Net cash provided by operating activities	153,167	129,312
Cash flows from investing activities
Purchases of businesses, net of cash acquired	0	(52,012)
Purchases of property, equipment and real estate	(49,079)	(45,905)
Proceeds from sale of property, equipment and real estate	633	4,153
Insurance proceeds	0	107
Net cash used in investing activities	(48,446)	(93,657)
Cash flows from financing activities
Proceeds from revolving credit facility	144,000	110,987
Repayments of proceeds from revolving credit facility	(144,000)	(110,987)
Repurchases of common stock under share repurchase program	(1,416)	(16,446)
Payments on finance lease obligations	(3,166)	(3,385)
Other financing activities, net	(12,192)	(6,001)
Net cash used in financing activities	(16,774)	(25,832)
Net increase in cash and cash equivalents	87,947	9,823
Cash and cash equivalents
Beginning of period	165,496	150,723
End of period	253,443	160,546
Supplemental disclosure of non-cash transactions
Accrued purchases of property and equipment	12,493	4,609
Acquisition-related holdback payments due at future date	4,280	1,549
Assets acquired under finance lease obligations	0	635
Right-of-use assets obtained in exchange for operating lease obligations	$ 11,870	$ 5,561