Geographic Information (Long-Lived Assets By Geographic Areas) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Long-Lived Assets	$ 867,686	$ 775,837	$ 667,323
United States [Member]
Segment Reporting Information [Line Items]
Long-Lived Assets	821,063	725,189	632,783
Canada [Member]
Segment Reporting Information [Line Items]
Long-Lived Assets	32,290	37,580	22,572
Other foreign countries [Member]
Segment Reporting Information [Line Items]
Long-Lived Assets	$ 14,333	$ 13,068	$ 11,968