Guarantor Subsidiaries (Schedule Of Guarantor Subsidiaries - Statement Of Cash Flows) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Guarantor Subsidairies [Line Items]
Net cash provided by operating activities	$ 8,141	$ 10,381
Capital expenditures	(5,406)	(12,018)
Business combinations, net of cash acquired		(415)
Other sources/(uses) - net	78	311
Net cash used by investing activities	(5,328)	(12,122)
Change in cash overdrafts payable	(3,165)	226
Dividends paid to shareholders	(3,367)	(3,072)
Capital stock surrendered to pay taxes on stock-based compensation	(3,389)	(1,431)
Proceeds from exercise of stock options	10,168	1,042
Realized excess tax benefit on share based compensation	1,891	797
Debt issuance costs	(1,107)
Other sources/(uses) - net	(419)	312
Net cash provided/(used) by financing activities	612	(2,126)
Increase/(Decrease) in Cash and Cash Equivalents	3,425	(3,867)
Cash and cash equivalents at beginning of year	69,531	38,081
Cash and cash equivalents at end of period	72,956	34,214
Parent [Member]
Guarantor Subsidairies [Line Items]
Net cash provided by operating activities	(4,511)	(5,365)
Capital expenditures	(10)	(14)
Other sources/(uses) - net	(16)	220
Net cash used by investing activities	(26)	206
Change in cash overdrafts payable	(554)	(46)
Change in intercompany accounts	6,731	1,607
Dividends paid to shareholders	(3,367)	(3,072)
Capital stock surrendered to pay taxes on stock-based compensation	(3,389)	(1,431)
Proceeds from exercise of stock options	10,168	1,042
Realized excess tax benefit on share based compensation	1,891	797
Debt issuance costs	(1,107)
Other sources/(uses) - net	(4)	(4)
Net cash provided/(used) by financing activities	10,369	(1,107)
Increase/(Decrease) in Cash and Cash Equivalents	5,832	(6,266)
Cash and cash equivalents at beginning of year	56,342	32,470
Cash and cash equivalents at end of period	62,174	26,204
Guarantor Subsidiaries [Member]
Guarantor Subsidairies [Line Items]
Net cash provided by operating activities	12,302	14,625
Capital expenditures	(5,278)	(11,664)
Business combinations, net of cash acquired		(415)
Other sources/(uses) - net	71	113
Net cash used by investing activities	(5,207)	(11,966)
Change in cash overdrafts payable	(2,611)	272
Change in intercompany accounts	(6,570)	(841)
Net cash provided/(used) by financing activities	(9,181)	(569)
Increase/(Decrease) in Cash and Cash Equivalents	(2,086)	2,090
Cash and cash equivalents at beginning of year	4,674	(1,422)
Cash and cash equivalents at end of period	2,588	668
Non-Guarantor Subsidiaries [Member]
Guarantor Subsidairies [Line Items]
Net cash provided by operating activities	350	1,121
Capital expenditures	(118)	(340)
Other sources/(uses) - net	23	(22)
Net cash used by investing activities	(95)	(362)
Change in intercompany accounts	(161)	(766)
Other sources/(uses) - net	(415)	316
Net cash provided/(used) by financing activities	(576)	(450)
Increase/(Decrease) in Cash and Cash Equivalents	(321)	309
Cash and cash equivalents at beginning of year	8,515	7,033
Cash and cash equivalents at end of period	$ 8,194	$ 7,342