Intangible Assets and Goodwill (Details) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014 Customer relationships	Dec. 31, 2013 Customer relationships	Mar. 31, 2014 Supplier relationships	Dec. 31, 2013 Supplier relationships	Mar. 31, 2014 Software & technology	Dec. 31, 2013 Software & technology	Mar. 31, 2014 Trademarks & trade names	Dec. 31, 2013 Trademarks & trade names	Mar. 31, 2014 Non-compete agreements	Dec. 31, 2013 Non-compete agreements	Mar. 31, 2014 Total intangible assets	Dec. 31, 2013 Total intangible assets
Finite lived intangible assets
Gross Carrying Amount			$ 350,929,000	$ 354,373,000	$ 29,000,000	$ 29,000,000	$ 167,276,000	$ 167,009,000	$ 34,378,000	$ 35,366,000	$ 7,448,000	$ 7,407,000	$ 589,031,000	$ 593,155,000
Accumulated Amortization			(254,937,000)	(251,388,000)	(25,738,000)	(25,013,000)	(156,796,000)	(155,009,000)	(33,264,000)	(33,985,000)	(7,418,000)	(7,373,000)	(478,153,000)	(472,768,000)
Net Carrying Amount	110,878,000		95,992,000	102,985,000	3,262,000	3,987,000	10,480,000	12,000,000	1,114,000	1,381,000	30,000	34,000	110,878,000	120,387,000
Finite Lived Intangible Assets Amortization Expense	$ 6,000,000	$ 9,000,000