Reporting Segments Schedule of revenues by geographic area (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Segment Reporting Information [Line Items]
Total revenue	$ 277,114	$ 277,916	$ 263,363	$ 269,466	$ 270,543	$ 279,390	$ 274,398	$ 280,627	$ 1,087,859	$ 1,104,958	$ 1,059,803
US
Segment Reporting Information [Line Items]
Total revenue									824,228	869,679	889,671
Canada
Segment Reporting Information [Line Items]
Total revenue									162,252	144,089	99,541
UK
Segment Reporting Information [Line Items]
Total revenue									79,743	59,967	55,900
Other
Segment Reporting Information [Line Items]
Total revenue									$ 21,636	$ 31,223	$ 14,691