Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Cash Flows from Operating Activities
Net income	$ 95,396	$ 99,967
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	20,522	19,046
Stock option expense	8,018	7,305
Litigation settlement	6,000
(Benefit)/provision for deferred income taxes	(2,769)	2,173
Noncash long-term incentive compensation	2,506	2,942
Asset impairment loss	2,266
Noncash directors' compensation	767	766
Amortization of debt issuance costs	153	288
Amortization of restricted stock awards		446
Changes in operating assets and liabilities:
Increase in accounts receivable	(16,613)	(6,057)
Increase in inventories	(631)	(362)
Increase in prepaid expenses	(2,301)	(113)
Decrease in accounts payable and other current liabilities	(4,175)	(14,909)
Change in current income taxes	(2,249)	10,136
Increase in other assets	(4,653)	(5,667)
Increase in other liabilities	5,833	4,889
Other sources	837	186
Net cash provided by operating activities	108,907	121,036
Cash Flows from Investing Activities
Capital expenditures	(28,312)	(23,872)
Business combinations		(1,875)
Other (uses)/sources	(137)	533
Net cash used by investing activities	(28,449)	(25,214)
Cash Flows from Financing Activities
Payments on revolving line of credit	(227,000)	(281,150)
Proceeds from revolving line of credit	222,800	358,350
Purchases of treasury stock	(71,926)	(84,304)
Proceeds from exercise of stock options	16,517	20,209
Capital stock surrendered to pay taxes on stock-based compensation	(14,884)	(21,022)
Dividends paid	(9,567)	(9,016)
Change in cash overdrafts payable	1,710	(711)
Payments on other long-term debt		(75,000)
Debt issuance costs		(968)
Other sources/(uses)	384	(663)
Net cash used by financing activities	(81,966)	(94,275)
Increase in Cash and Cash Equivalents	(1,508)	1,547
Cash and cash equivalents at beginning of year	4,831	11,121
Cash and cash equivalents at end of period	$ 3,323	$ 12,668