Geographic Information (Tables)

12 Months Ended

Dec. 31, 2012

Segments, Geographical Areas [Abstract]

Revenues By Geographic Areas

Revenues	2012		2011	2010
United States	$	2,798,124	2,474,805	2,067,860
Canada	218,570		198,592	145,078
Other foreign countries	116,883		93,462	56,533
	$	3,133,577	2,766,859	2,269,471

Long-Lived Assets By Geographic Areas

Long-Lived Assets	2012		2011	2010
United States	$	495,609	426,329	361,083
Canada	15,954		11,105	9,536
Other foreign countries	17,613		11,376	6,814
	$	529,176	448,810	377,433