Intangible Assets and Goodwill (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014 Customer relationships	Dec. 31, 2013 Customer relationships	Jun. 30, 2014 Supplier relationships	Dec. 31, 2013 Supplier relationships	Jun. 30, 2014 Software & technology	Dec. 31, 2013 Software & technology	Jun. 30, 2014 Trademarks & trade names	Dec. 31, 2013 Trademarks & trade names	Jun. 30, 2014 Non-compete agreements	Dec. 31, 2013 Non-compete agreements	Jun. 30, 2014 Total intangible assets	Dec. 31, 2013 Total intangible assets
Finite lived intangible assets
Gross Carrying Amount					$ 351,291,000	$ 354,373,000	$ 29,000,000	$ 29,000,000	$ 167,691,000	$ 167,009,000	$ 34,447,000	$ 35,366,000	$ 7,483,000	$ 7,407,000	$ 589,912,000	$ 593,155,000
Accumulated Amortization					(261,254,000)	(251,388,000)	(26,463,000)	(25,013,000)	(158,411,000)	(155,009,000)	(33,566,000)	(33,985,000)	(7,458,000)	(7,373,000)	(487,152,000)	(472,768,000)
Net Carrying Amount	102,760,000		102,760,000		90,037,000	102,985,000	2,537,000	3,987,000	9,280,000	12,000,000	881,000	1,381,000	25,000	34,000	102,760,000	120,387,000
Finite Lived Intangible Assets Amortization Expense	$ 6,000,000	$ 9,000,000	$ 12,000,000	$ 18,000,000