Supplemental Guarantor Financial Information (Condensed Consolidating Statements Of Cash Flows) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Net cash (used in) provided by operating activities	$ 41,380	$ 18,741
Additions to property and equipment	(15,145)	(21,324)
Payments for exclusive license agreements, site acquisition costs and other intangible assets	(792)	(362)
Acquisitions, net of cash acquired	(12,587)	(250)
Net cash used in investing activities	(28,524)	(21,936)
Proceeds from borrowing of long-term debt	57,200	53,700
Repayments of long-term debt and capital leases	(58,169)	(49,470)
Payment of contingent consideration	(250)
Repayments of borrowings under bank overdraft facility, net		(212)
Proceeds from exercises of stock options	247	1,264
Repurchase of capital stock	(3,804)	(1,406)
Excess tax benefit from stock-based compensation expense	3,966
Net cash provided by financing activities	(810)	3,876
Effect of exchange rate changes on cash	219	(44)
Net increase (decrease) in cash and cash equivalents	12,265	637
Cash and cash equivalents as of beginning of period	13,861	5,576
Cash and cash equivalents as of end of period	26,126	6,213
Parent [Member]
Net cash (used in) provided by operating activities	(6,454)	(5,426)
Investment in subsidiary	(13,327)
Funding of intercompany notes payable	(35,656)	(46,621)
Payments received on intercompany notes payable	55,624	47,205
Net cash used in investing activities	6,641	584
Proceeds from borrowing of long-term debt	57,200	53,700
Repayments of long-term debt and capital leases	(57,800)	(48,700)
Proceeds from exercises of stock options	247	1,264
Repurchase of capital stock	(3,804)	(1,406)
Excess tax benefit from stock-based compensation expense	3,966
Net cash provided by financing activities	(191)	4,858
Net increase (decrease) in cash and cash equivalents	(4)	16
Cash and cash equivalents as of beginning of period	5	1
Cash and cash equivalents as of end of period	1	17
Guarantors [Member]
Net cash (used in) provided by operating activities	40,898	21,950
Additions to property and equipment	(11,128)	(15,799)
Payments for exclusive license agreements, site acquisition costs and other intangible assets	(784)	(330)
Funding of intercompany notes payable		(4,800)
Acquisitions, net of cash acquired		(28)
Net cash used in investing activities	(11,912)	(20,957)
Repayments of long-term debt and capital leases	(3)	(3)
Proceeds from intercompany notes payable	35,204	46,395
Repayments of intercompany notes payable	(55,624)	(47,205)
Payment of contingent consideration	(250)
Net cash provided by financing activities	(20,673)	(813)
Net increase (decrease) in cash and cash equivalents	8,313	180
Cash and cash equivalents as of beginning of period	10,674	4,721
Cash and cash equivalents as of end of period	18,987	4,901
Non-Guarantors [Member]
Net cash (used in) provided by operating activities	6,937	2,217
Additions to property and equipment	(4,017)	(5,525)
Payments for exclusive license agreements, site acquisition costs and other intangible assets	(8)	(32)
Intercompany fixed asset mark-up	(1)
Acquisitions, net of cash acquired	(12,587)	(222)
Net cash used in investing activities	(16,613)	(5,779)
Repayments of long-term debt and capital leases	(366)	(767)
Proceeds from intercompany notes payable	452	5,026
Repayments of borrowings under bank overdraft facility, net		(212)
Issuance of capital stock	13,327
Net cash provided by financing activities	13,413	4,047
Effect of exchange rate changes on cash	219	(44)
Net increase (decrease) in cash and cash equivalents	3,956	441
Cash and cash equivalents as of beginning of period	3,182	854
Cash and cash equivalents as of end of period	7,138	1,295
Elimination [Member]
Net cash (used in) provided by operating activities	(1)
Intercompany fixed asset mark-up	1
Investment in subsidiary	13,327
Funding of intercompany notes payable	35,656	51,421
Payments received on intercompany notes payable	(55,624)	(47,205)
Net cash used in investing activities	(6,640)	4,216
Proceeds from intercompany notes payable	(35,656)	(51,421)
Repayments of intercompany notes payable	55,624	47,205
Issuance of capital stock	(13,327)
Net cash provided by financing activities	$ 6,641	$ (4,216)