Restructuring Charges (Details) (USD $)			3 Months Ended				12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended		9 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Dec. 31, 2012 Restructuring Plan 2012	Mar. 31, 2013 Restructuring Plan 2012 Employee separation costs	Mar. 31, 2013 Restructuring Plan 2011	Mar. 31, 2013 Restructuring Plan 2011 Employee separation costs	Dec. 31, 2011 Restructuring Plan 2011 Employee separation costs	Mar. 31, 2013 Restructuring Plan 2011 Consolidation of leased facilities	Dec. 31, 2011 Restructuring Plan 2011 Lease abandonment	Dec. 31, 2010 Restructuring Plan 2010	Dec. 31, 2011 Restructuring Plan 2010	Dec. 31, 2010 Restructuring Plan 2010 Employee separation costs	Dec. 31, 2010 Restructuring Plan 2010 Consolidation of leased facilities	Sep. 30, 2012 Restructuring Plan 2010 Consolidation of leased facilities
Restructuring Charges.
Estimated related cost savings due to restructuring plan			$ 20,000,000
Restructuring charges							19,200,000		4,300,000	2,300,000	800,000	100,000	2,200,000
Restructuring Charges
Balance at the beginning of the period	8,486,000	12,295,000		6,908,000	3,215,000	117,000		3,098,000						2,172,000
Utilized - cash				(3,428,000)	(260,000)	(12,000)		(248,000)						(98,000)
Other				(23,000)
Balance at the end of the period	$ 8,486,000	$ 12,295,000		$ 3,457,000	$ 2,955,000	$ 105,000		$ 2,850,000						$ 2,074,000