Carrying Amount and Accumulated Amortization of Other Intangible Assets (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 248,173	$ 174,459
Accumulated Amortization	(54,359)	(46,559)
Net Balance	193,814	127,900
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	228,183	157,364
Accumulated Amortization	(40,324)	(33,727)
Net Balance	187,859	123,637
Purchased contracts
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	10,729	10,823
Accumulated Amortization	(10,691)	(10,549)
Net Balance	38	274
Trademarks and tradenames
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	8,820	5,830
Accumulated Amortization	(3,098)	(2,096)
Net Balance	5,722	3,734
Covenant not to compete
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	441	442
Accumulated Amortization	(246)	(187)
Net Balance	$ 195	$ 255