Supplemental Guarantor Information Consolidating Condensed Statement of Cash Flows (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided (Used) by Operating Activities	$ 99,078,000	$ 122,207,000	$ 155,663,000
Investing Activities
Purchases of property and equipment	(22,160,000)	(17,353,000)	(17,999,000)
Proceeds from sale of property and equipment	64,000	36,000	1,163,000
Business acquisitions, net of cash acquired	(42,430,000)	(13,725,000)	0
Other long-term assets	(724,000)	801,000	601,000
Other	(13,000)	(376,000)	(447,000)
Net Cash Used for Investing Activities	(65,263,000)	(30,617,000)	(16,682,000)
Financing Activities
Proceeds from revolving lines of credit and long-term borrowings	450,595,000	708,742,000	400,123,000
Payments on revolving lines of credit and long-term borrowings	(454,567,000)	(751,660,000)	(553,436,000)
Proceeds from exercise of stock options	4,139,000	2,912,000	1,628,000
Payment of financing costs	(24,113,000)	(30,329,000)	0
Payment of dividends	(1,588,000)	(1,612,000)	(1,605,000)
Purchase of treasury stock	(21,548,000)	(5,687,000)	0
Net Cash Provided (Used) by Financing Activities	(47,082,000)	(77,634,000)	(153,290,000)
Effect of exchange rate changes on cash	(271,000)	(2,995,000)	4,294,000
Increase (decrease) in cash and cash equivalents	(13,538,000)	10,961,000	(10,015,000)
Cash and cash equivalents at beginning of year	48,462,000	37,501,000	47,516,000
Cash and cash equivalents at end of year	34,924,000	48,462,000	37,501,000
The Company (Parent) [Member]
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided (Used) by Operating Activities	38,724,000	101,658,000	154,367,000
Investing Activities
Purchases of property and equipment	(6,887,000)	(7,281,000)	(6,733,000)
Proceeds from sale of property and equipment	0	0	5,000
Business acquisitions, net of cash acquired	0	0
Other long-term assets	(731,000)	291,000	737,000
Other	(219,000)	153,000	(579,000)
Net Cash Used for Investing Activities	(7,837,000)	(6,837,000)	(6,570,000)
Financing Activities
Proceeds from revolving lines of credit and long-term borrowings	450,595,000	689,022,000	400,123,000
Payments on revolving lines of credit and long-term borrowings	(438,766,000)	(751,660,000)	(552,294,000)
Proceeds from exercise of stock options	4,139,000	2,912,000	1,628,000
Payment of financing costs	(24,113,000)	(30,329,000)
Payment of dividends	(1,588,000)	(1,612,000)	(1,605,000)
Purchase of treasury stock	(21,548,000)	(5,687,000)
Net Cash Provided (Used) by Financing Activities	(31,281,000)	(97,354,000)	(152,148,000)
Effect of exchange rate changes on cash	0	0	0
Increase (decrease) in cash and cash equivalents	(394,000)	(2,533,000)	(4,351,000)
Cash and cash equivalents at beginning of year	4,036,000	6,569,000	10,920,000
Cash and cash equivalents at end of year	3,642,000	4,036,000	6,569,000
Combined Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided (Used) by Operating Activities	49,396,000	15,427,000	1,823,000
Investing Activities
Purchases of property and equipment	(5,316,000)	(1,567,000)	(1,875,000)
Proceeds from sale of property and equipment	16,000	0	0
Business acquisitions, net of cash acquired	(42,430,000)	(13,725,000)
Other long-term assets	0	(11,000)	(122,000)
Other	73,000	(174,000)	416,000
Net Cash Used for Investing Activities	(47,657,000)	(15,477,000)	(1,581,000)
Financing Activities
Proceeds from revolving lines of credit and long-term borrowings	0	0	0
Payments on revolving lines of credit and long-term borrowings	(2,111,000)	0	0
Proceeds from exercise of stock options	0	0	0
Payment of financing costs	0	0
Payment of dividends	0	0	0
Purchase of treasury stock	0	0
Net Cash Provided (Used) by Financing Activities	(2,111,000)	0	0
Effect of exchange rate changes on cash	0	0	0
Increase (decrease) in cash and cash equivalents	(372,000)	(50,000)	242,000
Cash and cash equivalents at beginning of year	2,476,000	2,526,000	2,284,000
Cash and cash equivalents at end of year	2,104,000	2,476,000	2,526,000
Combined Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided (Used) by Operating Activities	65,516,000	44,442,000	105,575,000
Investing Activities
Purchases of property and equipment	(9,957,000)	(8,505,000)	(9,391,000)
Proceeds from sale of property and equipment	48,000	36,000	1,158,000
Business acquisitions, net of cash acquired	0	0
Other long-term assets	7,000	521,000	(14,000)
Other	133,000	(355,000)	(284,000)
Net Cash Used for Investing Activities	(9,769,000)	(8,303,000)	(8,531,000)
Financing Activities
Proceeds from revolving lines of credit and long-term borrowings	0	19,720,000	0
Payments on revolving lines of credit and long-term borrowings	(13,690,000)	0	(1,142,000)
Proceeds from exercise of stock options	0	0	0
Payment of financing costs	0	0
Payment of dividends	(54,558,000)	(39,320,000)	(106,102,000)
Purchase of treasury stock	0	0
Net Cash Provided (Used) by Financing Activities	(68,248,000)	(19,600,000)	(107,244,000)
Effect of exchange rate changes on cash	(271,000)	(2,995,000)	4,294,000
Increase (decrease) in cash and cash equivalents	(12,772,000)	13,544,000	(5,906,000)
Cash and cash equivalents at beginning of year	41,950,000	28,406,000	34,312,000
Cash and cash equivalents at end of year	29,178,000	41,950,000	28,406,000
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided (Used) by Operating Activities	(54,558,000)	(39,320,000)	(106,102,000)
Investing Activities
Purchases of property and equipment	0	0	0
Proceeds from sale of property and equipment	0	0	0
Business acquisitions, net of cash acquired	0	0
Other long-term assets	0	0	0
Other	0	0	0
Net Cash Used for Investing Activities	0	0	0
Financing Activities
Proceeds from revolving lines of credit and long-term borrowings	0	0	0
Payments on revolving lines of credit and long-term borrowings	0	0	0
Proceeds from exercise of stock options	0	0	0
Payment of financing costs	0	0
Payment of dividends	54,558,000	39,320,000	106,102,000
Purchase of treasury stock	0	0
Net Cash Provided (Used) by Financing Activities	54,558,000	39,320,000	106,102,000
Effect of exchange rate changes on cash	0	0	0
Increase (decrease) in cash and cash equivalents	0	0	0
Cash and cash equivalents at beginning of year	0	0	0
Cash and cash equivalents at end of year	$ 0	$ 0	$ 0