Geographic Information (Long-Lived Assets By Geographic Areas) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Segment Reporting Information [Line Items]
Long-Lived Assets	$ 529,176	$ 448,810	$ 377,433
United States [Member]
Segment Reporting Information [Line Items]
Long-Lived Assets	495,609	426,329	361,083
Canada [Member]
Segment Reporting Information [Line Items]
Long-Lived Assets	15,954	11,105	9,536
Other Foreign Countries [Member]
Segment Reporting Information [Line Items]
Long-Lived Assets	$ 17,613	$ 11,376	$ 6,814