Goodwill (Tables)

12 Months Ended

Dec. 31, 2012

Goodwill

Schedule of changes in carrying amounts of goodwill by reportable segment

	Region One		Region Two		Region Three			Region Four		Region Five		Total
Balance as of December 31, 2010	$	65,396	$	3,760	$	37,177		$	22,577	$	3,286	$	132,196
Acquired during the period		73		—		—			—		—		73
Contingent payments related to acquisitions		228		—		34			—		—		262
Foreign currency translation		—		—		(114	)		—		—		(114	)
Balance as of December 31, 2011	$	65,697	$	3,760	$	37,097		$	22,577	$	3,286	$	132,417
Acquired during the period		127,782		28,485		28,893			40,044		81,395		306,594
Contingent payments related to acquisitions		279		—		53			—		—		332
Foreign currency translation		—		—		138			—		—		138
Balance as of December 31, 2012	$	193,758	$	32,245	$	66,181		$	62,621	$	84,681	$	439,486