Summary of Significant Accounting Policies (Details 8) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Employee severance	Dec. 31, 2011 Employee severance	Dec. 31, 2010 Employee severance	Dec. 31, 2012 Office closures	Dec. 31, 2011 Office closures	Dec. 31, 2010 Office closures	Dec. 31, 2012 Unfavorable contract	Dec. 31, 2011 Unfavorable contract	Dec. 31, 2009 Unfavorable contract
Exit costs related to discontinued activities and personnel
Balance at the beginning of period	$ 2,500,000	$ 2,100,000	$ 3,200,000	$ 800,000		$ 100,000	$ 1,300,000	$ 1,600,000	$ 2,600,000	$ 400,000	$ 500,000	$ 500,000
New Charges	4,500,000	1,100,000		4,500,000	1,100,000
Plus Interest Accretion and/or Less Cash Payments, net	(5,800,000)	(700,000)	(1,100,000)	(5,000,000)	(300,000)	(100,000)	(900,000)	(300,000)	(1,000,000)	100,000	(100,000)
Balance at the end of period	1,200,000	2,500,000	2,100,000	300,000	800,000		400,000	1,300,000	1,600,000	500,000	400,000	500,000
Share-Based Payments
Share-based compensation expense	17,470,000	12,430,000	4,805,000
Tax benefits recognized related to share-based awards	$ 0	$ 0	$ 900,000