Segment Information (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Segment Reporting Information [Line Items]
Revenue	$ 317,719	$ 287,499	$ 610,288	$ 553,135
Other Segments
Segment Reporting Information [Line Items]
Revenue	20,094	15,648	38,445	29,720
United States
Segment Reporting Information [Line Items]
Revenue	258,597	237,901	501,902	457,410
Canada
Segment Reporting Information [Line Items]
Revenue	$ 39,028	$ 33,950	$ 69,941	$ 66,005