Segment Disclosures (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Schedule of Revenue from External Customers
Total Revenue	$ 172,861	$ 183,800	$ 188,606	$ 220,827	$ 162,923	$ 177,349	$ 183,464	$ 210,069	$ 766,094	$ 733,805	$ 730,401
United States [Member]
Schedule of Revenue from External Customers
Total Revenue									764,439	732,140	728,850
Canada [Member]
Schedule of Revenue from External Customers
Total Revenue									$ 1,655	$ 1,665	$ 1,551