Lease Obligations (Narrative) (Details) (USD $)	3 Months Ended		9 Months Ended			12 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2010 Facility Closing [Member]	Sep. 30, 2013 Contract Termination [Member]	Dec. 31, 2012 Contract Termination [Member]
Operating Leased Assets [Line Items]
Lease expiration year, minimum			2014
Lease expiration year, maximum			2019
Percentage of increase in annual base rent, minimum	3.00%		3.00%
Percentage of increase in annual base rent, maximum	3.50%		3.50%
Lease exit costs	$ 227,000	$ 164,000	$ 359,000	$ 666,000		$ 9,700,000	$ 6,600,000	$ 9,000,000
Property and equipment write-off						5,400,000
Rent expense, net sublease income	900,000	1,000,000	2,800,000	2,600,000
Adjustment for accretion and changes in lease assumptions	200,000	200,000	400,000	700,000
Tenant improvement allowance			3,200,000
Rent expense	200,000	300,000	500,000	600,000
Deferred rent	$ 354,000		$ 354,000		$ 334,000