Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash Flows from Operating Activities
Net income	$ 137,992	$ 95,396
Adjustments to reconcile net income to net cash provided by operating activities:
Ununtilized CARES Act grant	39,236
Depreciation and amortization	28,012	20,522
Deferred payroll taxes	10,716
Stock option expense	10,113	8,018
Noncash long-term incentive compensation	3,527	2,506
Provision/(benefit) for deferred income taxes	2,717	(2,769)
Noncash directors' compensation	1,171	767
Provision for bad debts	871
Amortization of debt issuance costs	153	153
Asset impairment loss		2,266
Litigation settlement		6,000
Changes in operating assets and liabilities:
Decrease/(increase) in accounts receivable	6,696	(16,613)
Increase in inventories	(5)	(631)
Increase in prepaid expenses	(33)	(2,301)
Increase/(decrease) in accounts payable and other current liabilities	13,303	(4,175)
Change in current income taxes	23,725	(2,249)
Net change in lease assets and liabilities	1,287	(338)
Increase in other assets	(2,988)	(4,653)
Increase in other liabilities	1,383	5,833
Other (uses)/sources	(54)	1,175
Net cash provided by operating activities	277,822	108,907
Cash Flows from Investing Activities
Capital expenditures	(32,251)	(28,312)
Business combinations	(3,600)
Other sources/(uses)	473	(137)
Net cash used by investing activities	(35,378)	(28,449)
Cash Flows from Financing Activities
Payments on revolving line of credit	(264,900)	(227,000)
Proceeds from revolving line of credit	174,900	222,800
Purchases of treasury stock	(122,148)	(71,926)
Proceeds from exercise of stock options	19,440	16,517
Capital stock surrendered to pay taxes on stock-based compensation	(14,845)	(14,884)
Dividends paid	(10,238)	(9,567)
Change in cash overdrafts payable	(9,849)	1,710
Other (uses)/sources	(586)	384
Net cash used by financing activities	(228,226)	(81,966)
Increase/(decrease) in Cash and Cash Equivalents	14,218	(1,508)
Cash and cash equivalents at beginning of year	6,158	4,831
Cash and cash equivalents at end of period	$ 20,376	$ 3,323