SEGMENT REPORTING (Schedule of Financial Data by Reporting Segment) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Statements of operations:
Net revenues	$ 134,625	$ 130,570	$ 132,178	$ 129,492	$ 125,771	$ 125,892	$ 127,015	$ 126,603	$ 526,865	$ 505,281	$ 473,834
Depreciation									33,758	32,482	30,831
Amortization									3,496	3,981	6,365
Asset impairments									1,196	879	456
Interest expense									(7,152)	(7,167)	(9,954)
Interest income									117	49	46
Income tax expense									9,062	5,445	8,586
Operating income	3,078	8,582	11,506	11,571	10,253	8,690	11,395	11,088	34,737	41,426	35,956
Balance sheets:
Intangibles, net of amortization	78,637				7,384				78,637	7,384	10,906
Property and equipment, net	105,724				104,613				105,724	104,613	103,449
Total assets	698,108				545,803				698,108	545,803	542,821
Expenditures for long-lived assets:
Capital expenditures									31,774	32,338	30,100
Business dispositions									0	0	1,902
North America
Statements of operations:
Net revenues									345,354	336,836	316,231
Depreciation									27,244	26,901	25,933
Amortization									2,878	2,716	4,465
Asset impairments									238	861	440
Interest expense									(6,784)	(7,091)	(9,860)
Interest income									81	24	1
Income tax expense									6,104	(209)	8,340
Operating income									6,165	9,853	1,849
Balance sheets:
Intangibles, net of amortization	34,316				7,384				34,316	7,384	9,633
Property and equipment, net	85,639				86,396				85,639	86,396	87,745
Total assets	507,141				455,345				507,141	455,345	454,738
Expenditures for long-lived assets:
Capital expenditures									25,451	23,843	24,304
Business dispositions											1,902
Europe
Statements of operations:
Net revenues									115,118	105,488	97,986
Depreciation									4,123	3,369	2,949
Amortization									509	1,265	1,640
Asset impairments									958	18	16
Interest expense									(342)	(248)	44
Interest income									4	19	28
Income tax expense									2,730	5,206	3,121
Operating income									25,927	27,279	26,739
Balance sheets:
Intangibles, net of amortization	41,213				0				41,213	0	1,273
Property and equipment, net	13,629				12,208				13,629	12,208	10,041
Total assets	148,892				59,283				148,892	59,283	55,826
Expenditures for long-lived assets:
Capital expenditures									3,361	5,802	2,846
Business dispositions											0
Asia Pacific
Statements of operations:
Net revenues									66,393	62,957	59,617
Depreciation									2,391	2,212	1,949
Amortization									109	0	260
Asset impairments									0	0	0
Interest expense									(26)	172	(138)
Interest income									32	6	17
Income tax expense									228	448	(2,875)
Operating income									2,645	4,294	7,368
Balance sheets:
Intangibles, net of amortization	3,108				0				3,108	0	0
Property and equipment, net	6,456				6,009				6,456	6,009	5,663
Total assets	42,075				31,175				42,075	31,175	32,257
Expenditures for long-lived assets:
Capital expenditures									2,962	2,693	2,950
Business dispositions											$ 0