Carrying Amount and Accumulated Amortization of Other Intangible Assets (Detail) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Indefinite-lived Intangible Assets by Major Class [Line Items]
Gross Carrying Amount	$ 53,414	$ 48,291
Accumulated Amortization	(31,652)	(27,843)
Net Balance	21,762	20,448
Customer relationships
Indefinite-lived Intangible Assets by Major Class [Line Items]
Gross Carrying Amount	41,142	36,393
Accumulated Amortization	(21,559)	(18,855)
Net Balance	19,583	17,538
Purchased contracts
Indefinite-lived Intangible Assets by Major Class [Line Items]
Gross Carrying Amount	10,812	10,753
Accumulated Amortization	(9,484)	(8,504)
Net Balance	1,328	2,249
Trademarks and tradenames
Indefinite-lived Intangible Assets by Major Class [Line Items]
Gross Carrying Amount	1,376	1,062
Accumulated Amortization	(538)	(422)
Net Balance	838	640
Covenant not to compete
Indefinite-lived Intangible Assets by Major Class [Line Items]
Gross Carrying Amount	84	83
Accumulated Amortization	(71)	(62)
Net Balance	$ 13	$ 21